USB isolator (galvanic USB isolation):
Before getting into the second part of this review, I wanted to take a moment to describe the effect ofa small “tweak” that has been talked about out elsewhere (in head-fi.org), theUSB2ISO or ADUM isolator.
What this little dongle doesis that it provides galvanic isolation between the computer and whateverconverter is connected through USB.
Many USB converters have somesort of transformer at their spdif output stage but most of them have zero tolittle isolation on their usb input. While in theory, one proper transformerbetween the usb converter and the DAC is enough to protect, the USB noise canin fact affect the performance of the USB converter itself but also some cheappulse transformers do not block everything.
Anyway, for 35 euros, Idecided to give a try a try and see if the reports of people noticing bigimprovements through that little device held any truth.
During the 2 months I had thedevice I tried it mainly on 3 converters the Musiland, Teralink-X2 and A-GD DI.(The Hiface isn’t compatible with the little device).
The effects were rather similar but to different degrees. There wasalways a removing of digital grunge (in the highs), an improvement in clarity,imaging and soundstaging. On the Musiland the effect was dramatic as it madevery listenable while on the Digital Interface (with external Power suplly), itwas barely noticeable.
Below is how I would rate the converters from the most affected to theleast affected:
- Musiland (most affected)
- Direct USB input of my DAC (similar to the Musiland)
- Teralink-X2
- Teralink-X2 with external power supply
- Digital Interface
- Digital Interface with external power supply (barely noticeable)
So while I have foundthat the USB2ISO can improve the sound (with no drawbacks), I found thatdifferent converters reacted differently. The better the power supply of theconverter, the less it improvement there was with that little USB device.
I personally found that theeffect is well worth with all the devices I tried it with save for the DigitalInterface with the external power supply. For that specific configuration, theeffect is very subtle but noticeable with the revealing ALO recabled Beyer T1s.
Keep in mind that the effectof the USB isolator will depend on the quality of the PS of the computer beingused. When doing any critical listening, I either use my laptop running on batteryor plugged to a power filter (with the battery removed). So your mileage mayvary depending on your specific configuration.
Teralink-X2:
I got the Teralink-X2 whilemy Hiface was broken (due to the excessive weight of my Oyaide Digital cablewas applying to its usb solder) and was being repaired by m2tech.
The Teralink-X2 was a niceimprovement over the X1 by adding 24/96 capability (but like other Tenor basedconverters, it lacks 88.2K support) as well as improving the sound quality.
Both models (X1 and X2)seemed to share the same warm and smooth sound, but the X2 being the mostresolved of the 2.
While, its sound improved byadding an external power supply and the USB isolation, I felt that it wasalways lacking in realism of timber. The stock Hiface, while more lightlybalanced, seemed to be better at preserving the natural timber of instrumentsand voices.
By adding those tweaks, the subjective noise floor seemed to drop, thesoundstage was even bigger and more defined, the level of details increased,and the bass became more articulate. But whatever the improvements, it alwaysseemed to me there was something off: a slight out of focus of imaging andtimbers.
I have to admit that if I didn’t have a superior converter such as the batterypowered Hiface; I wouldn’t probably be able to pick up on those faults.
Overall, I used the Teralink-X2 the past few months as a back up unit wheneverthe Hiface batteries were depleted and needed recharging.
I would recommend the X2 forsomeone starting to build a system and needing a 24/96 usb transport for a veryaffordable amount. I personally felt the stock Hiface was better than theTeralink-X2 and require less hassle (external power supplies, usb cables, USBisolators).
Side Note:Keep in mind though that when I am describing the stock Hiface, I am referringto the performance of the older models with 2 big clocks. At one point duringthe life cycle, M2Tech used miniature clocks for the 44.1K multiplesfrequencies. Weirdly enough, it was about the same time new owners startedcomplaining about how thin, bright and forward sounding the stock Hiface was.
M2tech said the new miniatureclock had the same specs as the big but it seemed it has reverted back to thebig ones.
This was a non-issue for thebattery powered Hiface since the direct battery power supply to the clock makethe quality of the clock less relevant. (The better clocks have better powersupply noise rejection capabilities than lower end ones).
Jkeny’s modified Hiface:
Timber & Tonal balance:
While there is no shift in tonal balance per se, there are howeverdifferences between the stock Hiface and the modified one in the way theyaffect the DACs. (Edit: The more solid bassrepresentation of the modified Hiface changes the perceived tonal balance intoa more neutral one than the lighter sounding stock Hiface).
The most striking feature of the modded Hiface is a better extension at thefrequency extremes: the bass extends deeper and the highs extend higher and ina cleaner fashion than the Hiface.
In comparison to each other, the sound of the modded Hiface is fuller. But thisis different from the false warmth injected by some jittery converters. Whilethe Teralink X2, for instance, is indeed warmer than the stock Hiface, itachieves so by adding the same extra warmth and haze to all the sounds, whichreduces the overall resolution.
So what to expect from the modified Hiface? With well designed and neutralDACs, the sound gains in tonal density and realism.
The instruments are more easilyrecognized and … they gain in realism.
Another strength of the modded Hiface is the way it renders the specific timberof very close sounding instruments.
Listening for instance to the Concerto for 2 violins - Vivaldi, you can clearlyhear that Carmignola and Mullova are playing 2 different violins (Stradivariusand Guadagnini if my memory serves me well). The violins are not onlybeautifully rendered but they also have distinct tonal signatures. While somewarmer converters can make this album tolerable to listen to, they rob theinner details of the instruments and make everything sound the same.
Of course, this won’t be the case with every DAC, the better and the moretransparent the DAC, the more subtleties you will be able to enjoy.
Soundstage & Imaging:
Here, the modified Hiface achieves something really interesting. It can throw ahuge soundstage (if the components downstream are up to the task) whileretaining a superb imaging capability.
If we take the Teralink X2 for example, it can throw a pretty big soundstagebut it lacks depth and is fuzzy and blurry. After listening for a while to themodified Hiface I understood that part of what it was doing is to push thesoundstage further back which is good for headphone listening and with entrylevel DACs. However, by doing so, there is a blurring of the layering lines andlack of depth.
The Hiface on the other hand throws a smaller soundstage in comparison to theTeralink X2 but it is a lot more defined a layered.
What the modified Hiface does is to throw a bigger soundstage than any otherconverter. To be more specific, the soundstaging is upfront like the stockHiface but it has a tremendous depth which makes it seem a lot bigger overall.While listening to the modified Hiface, you just feel like having an openwindow into the representation.
I have previously described the stock Hiface as having a holographic imaging.Here the modified Hiface goes a little bit further. Thanks to its greater tonaldensity and to its more accurate timber, you get not only a holographic imagingof the performers, but you get a greater sense of realism. You feel there arereal persons breathing and performing in front of you.
From a technical point of view, the stock Hiface was already very good in thatregard. But whatever, the modified Hiface is doing, it seems to be moreconvincing emotionally speaking.
Overall, the modified Hiface makes it a lot easier to mentally “reconstruct”the place where the recorded event took place. It just makes more sense.
Dynamics:
I first thought that I wouldn’t have much to write about in this section of thereview. When listening to the modified everything was fine, I had hugemacro-dynamics and beautifully rendered micro-dynamics but I assumed that wascoming from the rest of the chain. It was until I reverted back to the TeralinkX2 and Stock Hiface that I noticed the difference.
When trying new gear, we get accustomed sometimes too quickly to the benefitsand it is only until we revert back to the old gear that we realize how far wehave come from.
Here, the modified Hiface was actually a pretty big step up in dynamics. Infact, reverting back to the stock Hiface (or worse to the Teralink X2), thesound become duller, with slowed transients.
Once again, since the modified Hiface is only a usb to spdif converter, thelimiting factor in most situation will probably be the DAC itself. But incomparison to other converters, the modified Hiface gave the most dynamicresults regardless of the Hiface. So my bet is that is this characteristic willbe audible in all DACs.
Transparency & Definition:
The Hiface has an excellent analyzing capability. It can dig very deep in therecordings but renders the information in a very natural way. While the stockHiface is slightly more upfront with the details, the modified Hiface has a lotmore low level details. With the right associated DAC, you can get a verydetailed and relaxed representation.
Personally, I have never heard in my system a converter as detailed and at thesame time as analog like as the modified Hiface.
On interesting thing I also mentioned in my review about the dac19dsp is thatwith the modified Hiface it is the first time I can clearly hear a bigimprovement on 24/96 files.
Before that, I used to have a hard time distinguishing properly upsampled 16/44data to 24/96 from the native 24/96 ones. In fact what I had realized is thatmost differences we hear going from 16/44 to 24/96 are due to the poorfiltering at 44.1. Even with my entry level dacs (emu 0404 usb, audio-gddac100, audio-gd FUN, Purepiper DAC A-1, Zero DAC), I can hear the differencesbetween 16/44 and 24/96 but simply because their digital filters are relativelypoor at 16/44.
With the modified Hiface associated to the dac19dsp, it was something else. Ireally heard an increase in resolution by going to 24/96.
Preliminary conclusion:
Contrary to what I am used to, I have made very few musical examples simplybecause it is very dependent on the associated DAC.
The modified Hiface is a very transparent device. It doesn’t have a sonicsignature of its own. As far as I could tell, the overall sonic signature willdepend more on the associated equipment and the recording itself than on themodified Hiface itself.
For more details about musical examples, I invite you to read my review of theDAC19DSP for which I used the modified Hiface as a transport. (See here:
http://www.head-fi.org/forums/f7/rev...ection-483899/).
While the modified version that jkeny sent me is still a prototype, I can saythat it by far the best converter I have listened to in my system. I wasexpecting a small improvement (since I considered the stock one beingexcellent) but I was totally surprised by the level of performance of themodified Hiface. Its effect on the sound was not subtle at all.
jkeny described the sound of the modified Hiface as similar to that ofexpensive analog and I couldn’t agree more: his modified Hiface make the otherconverters sound broken.
Personally, I have already asked jkeny if I could send him my stock Hiface tohave a similar mod done to it.
Audio-gd Digital Interface:
Preliminaryimpressions (after 2 days):
So far I have only listened toit in the following configuration: USB2ISO (usb isolator) - WireworldUltraviolet USB cable - Digital Interface (w/ external Power supply) - OyaideDB-510 - DAC19 DSP. I didn’t have time to try any other configuration, so keepthat in mind when reading my comments.
Below are some preliminaryimpressions:
- Excellentlow level details retrieval (similar to the modified Hiface)
- Excellentresolution: 24bit material is really perceived as superior to 16 bit equivalent(similar to the modified Hiface)
- Bigholographic soundstage, excellent imaging, but lacks a little bit in depth incomparison with the modified Hiface
- Excellenttop to bottom coherency, the timber and pitch of instruments sound veryrealistic (similar to the modified Hiface)
- Verysmooth and distortion free treble
- Excellenttransient speed
- Verydynamic sounding (perhaps even better than the modified Hiface)
- TonalBalance: a little soft sounding at 44.1K and neutral sounding at 96K
- Excellentupsampling algorithms (to 96K): No loss in the low level details ornaturalness, the tonal balance improves (in my system) and images snap intofocus.
Overall, I feel that theJkeny’s modified Hiface performs at a slightly higher overall performance. Thedifference is also more noticeable at 44.1 and not so much at 96K.
However, when it is comparedto entry level usb converters (such as the Teralink X2, Musiland), the DigitalInterface is in another category.
Keep in mind that these aresome very early impressions that may change after I get more time listening tovarious recordings with the DI.
My only complaint so far isthat it doesn’t accept 88.2K.
Since I listened to Jkeny’smodified Hiface, I have felt that most other converters sounded fake andfatiguing in long term listening. The Digital Interface is the only otherconverter I have tried so far that seems to be good enough that I don’t feellike I am missing the sound of the modified Hiface when listening to it.
More on theDI (after 1 week)
External Power Supply
My Digital Interface camewith the external power supply. I did my trial on 2 systems:
System A: DI + Oyaide DB-510+ FUN + HD-650 (w/ stock cable)
System B: DI + Oyaide DB-510+ DAC19 DSP + C2 + Beyer T1s (w/ ALO upgrade cable)
On the less resolving systemA, the addition of the external power supply was barely audible. I would haveto spend a lot of time to hear any difference at all on that system.
On the more resolving systemB, the addition of the external power supply was clearly audible, but itsextent was dependant on whether the external power supply was plugged straightto the wall or through my Bada power filter.
When plugged directly to the wall outlet (or even through the unfiltered socketof my Bada filter), there was a slight increase in low level information and aslight tightening of the sound. However, it was nothing worth loosing sleepover.
On the other, hand when theexternal power supply was plugged in my power filter, the increase inresolution, frequency extension at the extremes, and soundstage depth were morenoticeable.
On my reference system, whenoperation straight from USB, the DI was better than the Teralink-X2 (withexternal power supply) but not as good as the modified Hiface. When using theexternal power supply, and plugged to a (good) power filter, the performancewas on the same level as the battery powered Hiface, and even better on someparameters (as explained below).
Drivers:
When I plugged my DI on my XPbased laptop, it was recognized as the Teralink-X2 since both devices use thesame Tenor usb chip. I have since played the DI through Foobar with theTeralink-X2’s ASIO drivers. I haven’t felt compelled to try otherconfigurations, and since it sounded good that way, I stuck with it for theremaining of the review, to keep everything constant.
Resolution and overall definition:
Like other high qualityconverters, the DI has 2 paradoxical qualities: on the one hand, there isplenty of resolution at low level listening, and on the other hand, it is alsopossible to raise the listening volume to extremely high levels without feelingany distortion or fatigue.
In my book, it means that weare dealing with true resolution and not fake resolution (that would be theresult of mid treble brightness for example).
While the increase inresolution over entry level converters was noticeable through my HD-650, it wasfar more obvious on the ALO recabled Beyer T1s.
Listening to “Open Your Ears - Chesky/Head-fi” which Ihave bought in both 16/44 and 24/96 versions, you get a clear sense of increasein perceived resolution when listening to the 24/96 version. The sound in thehigher resolution version is more open, less digital sounding, more detailedand “faster” (less transient distortions).
Upsampling the 16/44 files to24/96 (using the DI built-in upsampling) does improves slightly the focus andgets a little bit closer to the native 24/96 files. This is the first time Ifind that an upsampler provides me with a clear improvement and not just asideways shift. The excellent SoX upsampler didn’t sound as transparent but hasthe advantage of being very “tweakable” (you get to choose yourself the phaseand passband settings).
Throughout that test CD, youget to understand what high resolution is about. Very little low level detailsthat had been buried previously with entry level converters just reappear andmake for a very convincing and lifelike representation.
Though, I have to note thatthe DI seems to be more convincing at preserving the resolution of therecordings at 48K and 96K than it does at 88.2K frequencies. I assume that thefact the Hiface has 2 clocks (one for 44.1K multiple and a second one for 48K)helps keeping the same level of performance regardless of the sample rate.
BTW, when I talk about lowlevel details (for the DI vs. modified Hiface), I am talking about crazy lowlevel details. Even the Teralink-X2 can render the ambiance of the recordingvenue and the little noises (the hands of a performer on a flute, peoplecoughing, chair noises...). What the DI and the modified Hiface allow you tohear more clearly is the traffic noise outside a recording venue for example.So if your downstream components don’t have a vanishingly low subjective noisefloor, those differences might be a non-issue.
Soundstage and Imaging:
Regarding the soundstage, theDI gives excellent results similar to what I have achieved with Jkeny’smodified Hiface. With a “superior” headphone that uses angled drivers such asthe ALO Recabled Beyer T1, they both can throw a wide and believable soundstagein front of the listener.Unlike the somewhat big and diffused soundstage of the Teralink-X2 that isrelatively flat and undefined, the DI opens a very transparent window in frontof you.
The DI has superb imaging:the higher perceived resolution and contrast ratio help you to picture veryeasily individual performers and instruments. On very fine recordings (mostlyclassical), you can guess easily how the performer was facing the microphone,or how a soloist was playing his violin.
Timber and tonal Balance:
Among the things thatseparate the DI from entry level converters is the “weight” of therepresentation. Most built-in USB inputs (I have tried) and low performanceconverters seem to sound light. As for the stock Hiface, while it preservesrelatively well the timber of instruments, it could also be described aslightly balanced. The DI on the other hand, has a bass can reach very low andhas a very fine texture. The representation is very “weighty” without it beingbloated. To be more specific, and to give an example, the DI hits harder in thelows than the warm sounding Teralink- X2 but, at the same, the bass of the DIis more nuanced and articulate.
Like the Jkeny modifiedHiface, the DI uses its superior low frequency to anchor the images into thesoundstage and enhance the believability of the soundstage, which is a veryfragile parameter on headphone listening.
I have read one or two peopledescribing the DI as being dark sounding. Well, if you compare it to theMusiland, EMU0404 USB or (from memory) to the stock Hiface, it is definitelydarker.
But I feel that the DI is not as dark as the other converters are being brightsounding. The top 2 converters I tried in my system (Jkeny’s Hiface and the DI)have somewhat a rather similar tonal balance in comparison to brighter andharsher sounding entry level converters.
As I have said in my initial impressions, the DI seems to have a veryeven tonal balance throughout the frequency spectrum, with no apparentaberrations. Its bass is very deep articulate, and musical. Its midrange isvery transparent and the treble is very smooth and distortion free. In fact itstreble reminded somehow of what you get when moving from an entry level sigmadelta DAC to a good R2R DAC such as the dac19dsp. You get at first the sensethe there is less treble but the more you listen, the more you realize is thatwhat you get is in fact less digital hash and distortion and more true highfrequency information.
On one of my reference tracks, Concerto for Two Violins from Vivaldi,Carmignola and Mullova are playing 2 different violins: a Stradivarius and aGuadagnini. With an entry level converter such as the Musiland, the violinssound unnatural. On the DI, you not only get natural and realistic soundingviolins, but you can very clearly hear the slight tonal differences betweenStradivarius and Guadagnini. Of course, you need a pretty resolving system tohear such distinctions.
Also, thanks to its superiorlow level details retrieval, you hear the two soloists breathing, moving andyou can even guess how they were playing their violins and facing themicrophones.
The naturalness of therepresentation, coupled to the superior low level information retrieval, justmake the two violinists pop out in front of you. By closing your eyes, you canget fooled of having real instruments in front of you.
Dynamics
While I felt that the DI wasa match for the Jkeny’s modified Hiface on the soundstage and frequencyextension department, it felt though that, in my system, the modified Hifacehad the edge in low level details. My personal guess is that the battery powerhelps throwing a blacker background and increase the perception of low level details.This is the only area where the battery powered Hiface has a clear and distinctedge over the DI.
Transients seemedsubjectively faster on the DI than on the Batterypower Hiface, which might also explain why I felt that the DI was beingslightly more dynamic that the modified Hiface.
I believe that it has perhapsto do with the fact that John Kenny, the one who modified my Hiface aimed for avery “analog” sounding device while Kingwa, the designer of the DI aimed for arelatively neutral transport.
More importantly, theincrease in transient speed doesn’t come at the expense of decay of sounds. Infacts, I was quite surprised to notice that the decay of sounds was actuallylonger and truer on the Digital Interface (versus the battery powered Hiface).
My opinion is that Jkeny’s Hiface was tweaked to sound “analog” throughsmoothing the edges while the Digital Interface sounds “analog” by soundingmore realistic and truer to life (instead of rounding off the edges).
The attacks are sharp and thedecays seem to hang longer in the air than any other USB converter I have heardto date. This extended decay is very different from the haze the Teralink X2 isplagued with which adds the same euphonic coloration and warmth over allmaterial that goes through it.
While it was pretty obviousfrom the start that the DI had excellent macro-dynamics, it took me a few daysof listening to discover all the micro-dynamics subtleties it is capable of.Playing a well recorded voice or solo instruments, I got drawn into the musiclike never before. On my ALO recabled Beyer T1s, every tonal inflexion ormicro-dynamic shift of a voice or instrument was mesmerizing.
Since I got my T1s a fewmonths ago, I had been pretty impressed with their macro-dynamic capabilitiesbut would have never guessed they were capable of such micro-dynamicssubtleties.
Summary onthe DI:
Quick summary on the DI:
The good
- Excellentlow level resolution (better than all my converters save for Jkeny’s Hiface)
- Excellenttop to bottom coherency and very realistic timber: instruments and voices seemto be made from one piece (slightly better than Jkeny’s Hiface)
- Excellentfrequency extension at the extremes (similar to Jkeny’s Hiface)
- Excellentsoundstage and imaging capability (similar to Jkeny’s Hiface)
- Excellenttransient and dynamic capabilities (the best I have heard from a usb converter)
- Excellentupsampling algorithm
The bad
- Nosupport for 88.2K frequencies
- Alittle soft sounding at 44.1K (it can be overcome by upsampling to 96K)
- Theperformance of the external PS is affected by external factors (i.e need for apower filter)
Overall, I would say that theDI performed at a similar level as the battery powered Hiface. While themodified Hiface had a slight edge in low level details (in my system), theDigital Interface had a clearer edge in top to bottom coherency as well astransient speed and preservation of the natural decay of complex (non-amplified)instruments.
I predict that the modifiedHiface will provide better results with (aggressive sounding) Sigma Delta basedDACs (it will smooth out the edges), while the DI will do a better job withalready natural sounding R2R DAC such as Audio-gd’s PCM1704 DACs.
The differences between themare small enough that it will probably come down to personal performance andsystem synergy. Both units are a few steps from entry level converters such asthe Musiland / Teralink-X2.
In my system, and to my ears, I could sump up by saying that the DIsimply made beautiful music and didn’t call attention to itself. There areprobably other converters out there that can beat it in soundstage size,resolution, dynamics... but the good thing with the DI is that when you listento it (alone), it is very hard to pinpoint areas of weakness.
While it probably won’treplace a $1000 Empirical Audio usb transport, it will probably satisfy anyperson looking for their first good quality USB transport. My main and onlycomplaint, as I stated earlier, is that the DI (like the Teralink-X2, Bravo,Stello U2...) cannot handle 88.2K, which might not be such a big deal for mostpeople because of the material that is available is either at 44.1 (CDs), 48(movies) or 96 (most High Resolution music).
Conclusion of Part 2:
While I subjectivelypreferred the DI in my particular system, I believe that Jkeny’s Hiface isoverall superior because its performance is more consistent from one system toanother. The only thing you have to worry about when getting Jkeny’s Hiface isgetting a suitable battery charger and any functioning USB extender. With theDI, small tweaks (external power supply, power filter...) can have an effect onthe sound. So in that way, there is no guarantee that you will get the sameresults with the DI as reported here: they might be better or worse for allthat I know.
If we are looking at theperformance purely, Jkeny’s Hiface has the upper hand: I tried it with variousDACs from different makers, using different computers (laptops andworkstations) and the result has always been the same: excellent.
However, if we factor in theease of use, extra functionalities (upsampler, recloker) and build quality, theDI has the upper hand.
Last year, when I wasrecommending the Hiface to people, it was a very novel and breakthrough deviceand it was also cheaper (I paid 82.5 euros for it at the time). Today, thereare 24/96 (and higher) usb converters popping out everywhere.
In my personal opinion, thestock Hiface lost its value proposition, and I would rather recommend thecheaper Teralink-X2 for entry level set-ups, or the Digital Interface (withoutpower supply) for mid level set-ups.
At a slightly higher priceboth the A-gd Digital Interface (with the external power supply) and Jkeny’smodified Hiface seem to represent excellent price quality ratio. I canpersonally live with either one and I can’t say the same with other converters.For those willing to spend even more, there are very interesting USB converterssuch as the Audiophilleo, Empirical Audio converters, Weiss INT202... to name afew.