bcwang
500+ Head-Fier
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This is what I call an "Incremental Review", because I can go into so much detail that if I waited until I actually finished writing everything I want to post a review, it will never get posted. So expect an incomplete review at first, with more and more getting added as time goes by. It will feature high quality images to accompany the review which click through to 2MP size. It's an idea I had and this is my first attempt at one so we'll see how it goes.
Product: Nuforce uDac-2
A portable USB powered DAC with a built-in headphone amp. It also features a pair or RCA outputs controlled by the volume knob, and an SPDIF output.
Packaging:
Dimensions of packaging: 6" (7.1875" including hanger flap) x 6" x 1.375"
Nuforce has got the packaging retail ready. The uDac-2 comes in durable plastic box with a hang hole flap, the material is very thick and the box itself is unlikely to be damaged. You can see the device inside the box so a buyer can have a feel for the size of the unit. The back has specs of the device for those who may be comparing with other devices on the shelf. The box is rather plain otherwise, without the refinement a company like Sony or Monster Cable would otherwise embellish the packaging with. The box design looks a little generic, and on the shelf next to the big brands it would really give the feel of being one of those low cost Asian products without the budget to put into package design. However, functionally speaking I think it works well. The package looks the same after being used multiple times, with no creases, no ripped flaps, no torn paper from stickers...it essentially looks new.
Contents:
- uDac-2
- Instruction Manual
- 1 Meter ChingLung Hi-Speed USB 2.0 cable - AWM 2725 80 degree C VW-1 28AWG/1P and 24AWG/2C
The Manual doesn't have too much important info in it, the most pertinent being the specs and the warranty. The usb cable looks pretty decent. The warranty coverage is 1 year, and there is also a 30 day return period. It is known that Nuforce has no hassle with their 30 day return policy, if you don't like it you can return it for a full refund.
Product Details:
MSRP: $129
Dimensions of rectangular area: 2.67" x 1.65" x 0.83" (note: both the manual, box, and website have the dimensions wrong. I measured myself and got a far different depth)
Dimensions including all protrusions: 2.67" x 2.44" x 0.83"
Available Colors: Black, Silver, Red. Only the main body shell differs in color, the front and rear faceplates remain black.
Design:
- The body looks to be made of anodized aluminum with a matte finish.
- The body seems relatively scratch resistant and should pick up no noticeable wear when placed on normal surfaces it would come in contact with in daily listening use.
- I like the build quality better than many other audio equipment in this price range which is usually made of plastic. The unit seems very strong and solid. It feels quite heavy for the size, and shaking it around has no rattles of any kind.
- The Nuforce logo imprinted on the top and bottom of the case look nice, it is a stylish product overall.
- The connections are clearly labeled, the jacks are color coded as well. Red - right, White - left, Orange - coaxial digital out
- I wish it came with attachable rubber bumps of some sort. Being small and hard anodized aluminum, it tends to slide around a lot and will probably scratch your table.
- Visually it looks exactly the same as the original uDac. I see no way to visually tell them apart.
Volume Control:
- The knob is made of black plastic, the finish matches well with the aluminum finish, it doesn't look out of place.
- The knob is as large diameter as it can be due to the size of the uDac-2 itself. It's size makes it easy to make minute adjustments in volume and makes it easy to grip too.
- Off is 7:30 and full volume is 4:30. It clicks from off to on, then volume goes up.
- The volume knob on this unit is crooked, which you can obviously see when you turn it. One of the photos shows a view where you can see the angle of crookedness. I could not fix it by pressing on it but I didn't want to break it off. Hopefully this is not a common problem as it detracts from an otherwise high quality looking product.
- The uDac-2 is supposed to use a highly linear TOCOS volume control which is different than what is in the original uDac. It is supposed to track volume better between left and right especially at lower levels. I think I read that the volume ramp is also supposed to be more gentle so you can more easily control it at lower volumes and sensitive headphones than the uDac
- From my impressions when comparing this unit to a sample of the original uDac, I heard no obvious difference in tracking accuracy improvement. Both started off with one side slightly louder, raising the volume just a bit more on both of them match volumes up right away which is good. As you turn up the dial more, it seemed like the uDac-2 actually raised in volume at a slightly faster rate than the original uDac, counter to how I thought it was supposed to behave. Overall, I'd say the volume control of the two models don't differ very much. Of course there is always sample variation, but from the single samples of each model I can't say the volume control differed significantly. If the original uDac I had to compare with had one of the badly off ones I probably wouldn't be saying the same thing. Maybe on the average, the new volume control is more consistent in each unit matching volumes at low levels compared to the original one which had enough complaints where some units were really bad and some good enough. Whatever the case, the change was made to have a new volume control but my testing of it netted no obvious difference.
Inputs:
- Full size USB Type-B jack - The uDac2 only gets it's input as USB digital audio, it has no other inputs
- The uDac-2 supports 96khz 24bit usb audio, which is an improvement over the 48khz 16bit support of the original uDac.
- I like that it uses full size USB rather than mini or micro. The cable ends in this style are stronger, there are better cables available, and the jacks itself are probably less likely to break as well.
Outputs:
- Headphone out in the front - controlled by the volume knob, 1/8th inch jack
- RCA analog out pair in back - controlled by the volume knob, gold plated - This makes it possible to use this to drive an amp directly. If you want to use this as a line-out, you can just set the volume knob to 100%. It is a little hotter than many standard line-outs from other devices I tested, but still works fine without clipping my amps.
- RCA digital coaxial out in back - gold plated - I did not test this, but I believe it always outputs digital data now regardless of knob position. On the original uDac, the volume knob had to be set to off to have the coaxial send digital data. This jack can be used to get digital audio from your computer to your home theater receiver or higher performance DAC without a usb input. Since I haven't tested this feature in detail, I will just leave this as my only comment on this feature for now.
Crooked volume knob - The only build quality complaint
Usability:
- Most of the time the unit is great. Plug it into the computer, it becomes the default sound card, and sound goes through it.
- However, there are a couple of behavior differences when compared to the original uDac
1. The uDac does not let the windows volume control have any effect. The uDac-2 does change volume with the windows volume control. This means users must pay attention to make sure they have all volume controls related to the uDac-2 set at 100% if they want to get the best sound quality. This was not a worry with the original uDac. However, the advantage is people who have trouble trying to listen at lower volumes with highly sensitive IEMs can now do so by lowering the windows volume control and getting the volume pot out of that poor left-right tracking area.
2. A potential bug in the USB chip exists. In windows XP using asio4all, the uDac could be plugged in at any time after being setup once, and it would play in foobar. You could plug and unplug it all you want, and the next time you wanted to play, it would work. With the uDac-2, I believe there is a bug. I first noticed that after setting it up correctly (which took a while you'll see later), if the unit was unplugged and later plugged back in, it would not play and I had to go deal with the settings all over again. In fact, it was very difficult to setup the first time in asio4all. The problem is that the uDac-2 exposes an input pin like a recording device, but the uDac-2 cannot record. In asio4all you have to make sure you disable that pin and only enable the stereo output pin in order for it to work. This necessary step I'm sure messes up many people trying to use XP with asio4all and foobar.
I also think it's a bug because in OSX, the uDac-2 shows up both as an audio playback device and a recording device as well. Obviously the uDac-2 cannot record as it has no inputs.
3. The uDac could only play up to 48khz 16bit, the new chip can play up to 96khz at 24bit now. This gives you the ability to play hi-res recordings that are getting more common these days.
4. The iPad can support the original uDac through the USB camera kit from what I've read. However, the uDac-2 does not work on the iPad afaik.
Sound Comparison Setup:
To compare sound, I will test the uDac-2 against two other systems also capable of 96/24 playback and with a variety of headphones.
In Win7: Foobar -> Wasapi -> to.....
A. Nuforce uDac-2 with bundled usb cable - has a Sabre 9022 DAC and the advertised capability to support 16-300 ohm headphones.
B. Creative Labs X-Fi Fatal1ty Professional Series PCI sound card in audio creation mode, all DSP's off, bit matched playback, through Belkin 2M 1/8th extension (sorry, can't reach the jack comfortably for testing without the extension)
C. Nuforce HDP with Wireworld Starlight 1M usb cable powered through Pangea AC-9 powercord with stock power supply. For IEM tests, sound comes out of RCA jacks with volume pot at max volume with Nuforce 1.5M Transient RCA to 3.5mm cable into Pico Slim. The reason is I can't listen to HDP through any IEMs directly because the hiss and volume level is overpowering for me.
Giving relative sound among these 3 systems may help users place where the uDac-2 performs with specific headphones and music. System B is a very common sound card series (X-Fi) and gives a basic representation of a standard sound card audio. System C is quite a nice DAC/AMP that works well with a computer through USB. The uDac-2 can play anything these 2 systems can play out of a computer so it'll make for some good comparison testing.
Sound with different Headphones:
Shure SE530 - triple balanced armature, 18hz-19khz, 36 ohm impedance (@1khz), 119db/mw (1mw)
It's been a while since I've used this headphone, I don't remember this headphone being so bass light. Weird, I used to think this headphone had lots of bass, but I did come from an E4 when I went to the SE530. Anyway this headphone is one of my most sensitive pairs and at 36 ohm should be pretty easy to drive. However, this sensitivity also becomes its achilles heel when used with the uDac-2.
The first problem using this headphone with the uDac-2 has a clearly audible hiss with this headphone is plugged in. The hiss is louder than what you can hear when plugged into the X-Fi, where the X-Fi has a lower pitched and softer hiss, the uDac-2 has more energy in the hiss in the higher frequencies so it is more bothersome. With the HDP headphone out the hiss is so significant that I can't use it and thus have to test through the Pico Slim, which I hear no hiss at all in this comparison. With lots of music, I can hear the background hiss with the uDac-2 and it ruins the effect of a clean acoustic performance, or a silent concert hall, etc... Basically when you want pure blackness between notes, you don't get it with the SE530 paired with the uDac-2. To get a relative volume of the hiss, the uDac-2 hiss is significantly softer than the HDP headphone out, is softer than the hiss of the ipod video (5g), is louder than the hiss of the iphone 4 and 3gs, and is louder than the hiss of the X-Fi,
The second problem using this headphone with the uDac-2 is by the time the volume control equalizes both channels to be equivalent, for much music it is much too loud for my ears. For comparison, the X-Fi has no sound until the volume control hits 5, I can listen to many albums at this level, it is a good level. On this headphone, the sound on the uDac-2 equalizes at a level that is about 8 on the X-Fi. This is decent for many softer recordings but way too loud for many modern hip hop, pop, rock recordings. It will just blow my ears off trying to listen. For reference, this position on the uDac-2 dial is about 8-8:30.
On to actual sound comparisons. This is one of the headphones that I was thinking would show less difference between amps/sources being it is easy to drive and is so bass light and treble light that it would kind of mellow out and make things sound similar. However, I was surprised at the amount of difference between the 3 systems with the SE530. One of the first things noticed about the X-Fi is how poor the sound simply is compared to the uDac-2. You get an immediate improvement in clarity, all instruments sound more clear instead of blurry and veiled on the X-Fi. You also get a soundstage instead of what seems like no soundstage at all in comparison with the X-Fi. For example, when hearing a singer who is performing front and center, on the X-Fi you hear the singer and it is a wall of sound. With the uDac-2, the singer is focused and it sounds more like a person singing in front of you rather than 2 poorly placed speakers just broadcasting the singers voice. I don't know what the X-Fi does wrong to make it sound so diffuse, but the uDac-2 is a clear improvement in this area. However, compared to the HDP system, it is clear the uDac-2 is still far from perfect. The HDP gains much more focus and soundstage. However, I'd say the difference in focus and soundstage is much greater between the uDac-2 and X-Fi than it is between the HDP and uDac-2.
The bass on the se530 seem weak, but this is especially so when driven directly by the X-Fi. Where the X-Fi makes bass seem to not exist in certain songs where there are deep sustained notes, the uDac-2 makes it audible. The X-Fi kind of slides into the beginning of it, but dies down where the uDac-2 can sustain the note. This makes dance music with the boom boom boom much nicer to listen to. However, the uDac-2 bass still seems out of control with the SE530 somehow. You can hear it better, it is stronger, but is better in every way compared to the X-Fi, but it still feels sloppy. This is most evident once compared with the HDP system which has tight control over the bass. Where the uDac-2 seems to swell at bass hits, it doesn't have snap like the HDP. When the bass note transitions, it is slow with the uDac-2, tight with the HDP system, and nearly non-existent with the X-Fi. In one song, with the X-Fi, I could hear some bass notes that transitioned with the song, but it just sounded like a single bass note that was held and changed pitch at different times. With the uDac-2, you finally feel some texture to the sound, you know it's coming from an instrument now and it's not just a synthesized note. However, it is not until the HDP that you realize it is a bass being plucked for each note. I don't know if the HDP Dac is so much better than the uDac-2, or if it is the pico slim is a much better amplifier for the SE530 than the uDac-2. But it is obvious the uDac-2 is not at the level of the HDP. On the bass performance with this headphone I'd say the HDP system is about as much an improvement over the uDac-2 as the uDac-2 is over the X-Fi.
Now on to transient performance. When I first listened to the X-Fi with cymbal hits in music, it didn't sound like a cymbal much. It sounded like a millimeter thick felt pad laid on top of a cymbal and then hit with the stick. The sound had no attack, it had no clear ringing that you'd expect. The uDac-2 improves this quite a bit so you get a crisper hit. The same applies to the attack of the initial bowing sound of a stringed instrument like a Cello, that initial bite is lost with the X-Fi but can be heard with the uDac-2. Without that bite, you lose the rhythm, pace, and timing which that bite of the bow hairs into the string brings. The uDac-2 is much more exciting to listen to than the X-Fi when Yo-Yo ma plays aggressively with his Cello. You can feel the emotion of his playing that is lost with the smear of transients by the X-Fi. The HDP resolves more detail in the bite than the uDac-2 though, but the uDac-2 already makes things much more enjoyable than the X-Fi. The same goes for piano, the X-Fi smears it so it sounds like a synthesized keyboard and not a good one either. However, for piano the improvement with the uDac-2 is noticeable but less than the improvement the HDP brings to the piano. On the HDP where you can tell the percussive nature of the piano with the sharp attack of the initial note being struck and the sound of the decay, the uDac-2 rounds the attack a bit. But this is still bounds better than the X-Fi FM synthesized sound like piano that comes out. Again, this brings up whether the improvement in transient performance is a result of the amp having a hard time with the SE530 load, or the DAC in the HDP is really that much better. Maybe I'll have more to say as I move on to other headphones.
Where the X-Fi veils everything, blurs transients, mushes up fast instruments, has a blurry unfocused soundstage and gets congested all the time with complex music, the uDac-2 improves upon that. All sound is clearer, there actually is a soundstage now, instruments sound more like real instruments. However, at the same time it is also clear when hearing the HDP system that there is still lots of improvement available in these areas and the uDac-2 is not a holy grail of computer music playback, at least not with the SE530. So universally the uDac-2 is an improvement in almost every way to the X-Fi when paired with the SE530 except for 2 areas, excessive hiss and difficulty with using at lower volumes due to channel matching. But I believe there are many people who won't hear the hiss with this combination and will actually be playing well above the point of volume matching. I know my ears are on the sensitive side and I play at much lower volumes. At $129 which is about the price of the X-Fi, the uDac-2 is a much preferable device for music playback with the SE530 if you are one who does not have issue with the hiss or need to use below 9 o'clock on the volume dial. However, for someone like myself, I cannot recommend the uDac-2 with the SE530 as the hiss detracts too much from the experience, and some of my music is unlistenable due to high volumes.
Shure SRH840 - closed back full size, 44 ohm impedance (1khz), 102db/mw (1khz), 5hz-25khz
Grado RS1 - open air full size, 32 ohm impedance, 98db/1mv, 12hz-30khz
I put these two headphones together because the sound differences using the different sources was very similar. First, the differences are dramatically less between the sources using these two headphones than the SE530. This actually surprised me quite a bit as I expected the SE530 to be one of the headphones that you'd be able to tell less difference between the sources. First of all, there was no detectable hiss using these two headphones with the uDac-2...at least not in the not completely quiet environment I had to work with. And the sensitivity levels of these two headphones allows a good degree of control over volume which I did not have with the SE530. So basically there is no problem with the music being too loud and not having the ability to turn it down when using these two headphones. However, you still can't listen to louder music very very quietly or you'll hit the imbalance issue again, but it will be at moderate and comfortable volume.
The 3 sources had much closer bass response with these 2 headphones. The difference wasn't as dramatic as the SE530. In terms of control, the HDP still wins, but the uDac-2 seems to produce more bass overall than the other two. The difference is not so drastic, and the X-Fi is able to do pretty good with the bass as well. This time the bass is not vanishing with the X-Fi the way it was before. However, the definition in the uDac-2 is still greater than the X-Fi and still better again going to the HDP. However, it is not as noticeable compared to the SE530.
Much of the obvious sound transient differences are also gone when using these two headphones. First, cymbal hits on the X-Fi actually sound decent now. The improvement going to the uDac-2 is slight, and moving to the HDP again is only slight again. The difference is more in the detail of the resonance after the initial strike. Where the X-Fi seems to have little detail, the uDac-2 shows more detail, and again the HDP shows a bit more. However this time the difference is the uDac-2 is much closer to HDP performance than X-Fi. The same trend holds for drum snaps, guitar plucks, hand claps. The X-Fi is able to do much better now, and the improvement going to the uDac-2 is less, and even less when moving to the HDP this time. Overall though, the uDac-2 is closer to the HDP than the X-Fi in this regard. This is a good sign for the uDac-2.
So with a lot of the obvious things with sound characteristics that can be picked up with a quick listen much less obvious now, what is really different between the 3 sources? Well for starters, one is detail. Though you might feel similar bass punch and rumble using all 3, and similar clear cymbal hits and guitar plucks....the detail in the sound is significantly improved by the uDac-2 over the X-Fi. The X-Fi makes the sound, but the uDac-2 adds texture to make it more real. The HDP is not much ahead of the uDac-2 the way the uDac-2 is leaps ahead of the X-Fi in detail retrieval. While the X-Fi no longer sounds like it veils everything and sounds ok at first listen, once you compare it to the uDac-2 you notice it is much more of a flat sound without the detail that makes it sound like a real instrument. Some other aspects still remain true like before, the soundstage of the uDac-2 is much better than the X-Fi. With the HDP it is only slightly better than the uDac-2.
These two headphones must be much easier to drive for the X-Fi to sound so much closer to the other two sources. However, without any drawbacks of hiss and sensitivity issues when using these two headphones, I can definitely recommend getting the uDac-2 with these headphones. You are getting closer to the performance of the HDP and making music much more enjoyable than on the X-Fi. I think the differences heard now are the differences between the different DACs...the detail, soundstage, and presentation. With the SE530, I think the differences were the different amps handling capability of the IEM resulting in extremely different performance.
-Sennheiser HD800 - open air, 300 ohm impedance, 102db @ (1khz/1V rms), 15hz-44.1khz (-3db)
This is my main headphone and after listening to it again it is obvious why the Shure and Grado showed much less differences between sources than I would have expected. They just overall had less detail than what I normally hear out of the HD800. So with a reference headphone how do the 3 sources sound? Well one thing I learned is that even through an X-Fi sound card, the HD800 can sound pretty decent. However, with this headphone it also shows more apparent differences between the three sources.
Strangely, at least for my listening limits, all 3 sources easily got loud enough. In fact, at least based on the volume dial travel position, the uDac-2 seemed like it was louder at a lower volume setting than the HDP. That doesn't really mean the uDac-2 can get louder though, as who knows how the volume taper works out for the rest of the dial. However I wasn't about to blow my ears to try it out. Now what happens as you start raising the volume is the X-Fi starts to sound honky. It seems to be due to lack of drive power as it only happens at higher volumes, it seems to throw all sorts of artifacts into the sound. It makes it very painful to listen to loudly. With the uDac-2 and HDP however, both are able to scale up in volume cleanly and continue sounding good at the limits of my capability before it is to painful to keep it on.
When it comes to bass slam and deepness, the X-Fi has trouble delivering any slam, and maintaining sustained deep bass notes. The uDac-2 improves on the slam and power greatly, but seems to lack the texture in the bass the HDP brings. The HDP also improves the bass slam to a level above the uDac-2. However, it is clear the uDac-2 and HDP are well above the level of the X-Fi, especially as volume is raised and you want to feel the power. If you like it loud and clear with the HD800, the uDac-2 does plenty well in this arena compared to the X-Fi.
Though many instruments sound clear and sparkly with the X-Fi and HD800, voices in particular sound muffled for some reason. This is very apparent as you move to the uDac-2 how much singing voices clear up. Maybe it's the fact that we know how human voices are supposed to sound that any unnaturalness due to poor dac or amp performance become dramatically clear. Again, the HDP can improve upon the uDac-2 even more in this regard as voices gain more openness and detail but this seemed only apparent with the HD800. The other two full size headphones I did not have this impression.
The HD800 soundstages very well, and this is an area where you hear the X-Fi do a poor job compared to how well the uDac-2 performs. The uDac-2 presents a good soundstage with distinct placement of all instruments and singers, you can sense where everything is. In fact the uDac-2 does so much better when you switch to the X-Fi you think there is something wrong as the soundstage just collapses. Or maybe I should say all the instruments lose focus and blur together, that is really the effect I feel. Yes, the uDac-2 still gives up the precision the HDP has in placing sounds within the sound field, but it does so much a better job than the X-Fi.
When it comes to detail, the differences become very apparent with the HD800. When you move from the X-Fi to the uDac-2, it goes from a veiled like sound to clear sound. Violins that sound monotone and not really like stringed instruments on the X-Fi actually sound like violin with additional note emphasis and stringing detail on the uDac-2. Trumpets that have a smooth tone on the X-Fi have texture on the uDac-2. The difference is pretty dramatic in everything you listen to, the X-Fi is not a source you really want the revealing hd800 paired up with as you are not hearing so much that is in the recording. The HDP does trump the uDac-2 again as now as not just can you hear additional detail in the trumpet, you can hear the breath sounds and the initial push of air the player is doing on this one piece I was listening for. Initially hearing it on the uDac-2 I wasn't sure what it was but once heard with the HDP you can imagine exactly what that sound is.
Without going further into what is obvious now, the uDac-2 is a major step up with the HD800 compared to the X-Fi. And with the HDP, you get another big step up in performance over the uDac-2 which is more obvious with something as detailed and with such an open soundstage as the HD800.
Conclusion
I think the uDac-2 at $129 is one of the best bang for the buck values I've encountered. Well, maybe other than the original uDac which at $99 was an even better value if the sound is the same. But I never got to extensively listen to it to see if it was at the level of quality the uDac-2 is. However, the uDac is no longer available so that is moot point. Right now it will probably be hard to find something with this combination of features, build quality, and sound quality at such a price point. In fact, I can't think of another device near this price that I could recommend to friends who want to get into the path of an audiophile at an affordable price point. Just being a usb DAC/headphone amp at this price would be enough for me to recommend it, but this also has RCA line-out and coaxial digital out if you want to get computer audio to a home theater receiver digitally. Those are bonuses if you're one to find uses for those features.
The build quality is also amazing at this price point. Usually you find light plastic boxes with mini-jacks and sliding volume controls. Or maybe a usb stick sized device with a single shared input/output optical mini-jack port and the susceptibility to be snapped off if used on a laptop without care. In any case, this device looks like it will last a long time, coming with a durable full size usb jack, very solid RCA jacks, a supposedly high quality volume pot, and a thick anodized aluminum case. Plus, it looks pretty cool, who is to imagine such good sound comes from such a little box. I think it'll surprise a lot of people who haven't heard higher end audio before and are only used to computer sound. This device will up their quality quite a bit if they have good headphones to pair with it.
From a lot of the sound comments above, it may seem like the sound isn't that great with the HDP obviously being better. But do remember I am comparing this $129 product with a $449 product from the same company. That is a very different price range we are looking at and it was only used as a reference to see how far it can keep up in sound to something significantly more expensive. In overall sound, the HDP is still significantly better in my opinion. However one place where I find the uDac-2 better than the HDP is using with very sensitive IEMs. The hiss level is much more manageable on the uDac-2 than the HDP, though I feel neither do justice to sensitive IEMs the way the pico slim hooked through the HDP handled it. Maybe it's the fact that both were near the very beginning of their volume travel and they felt less dynamic and clear than the pico slim when driving the SE530. Compared to the X-Fi though, the uDac-2 is still a huge upgrade when using IEMs and if that is all your budget allows, I say go for it.
So my final word is if you want good sound below $150, the uDac-2 is a great way to get it! I actually have no better product to recommend to friends just getting into audio and don't want to spend too much.
Pluses
- Small and Durable build making it very solid and unlikely to be damaged if thrown into a bag with a bunch of other stuff
- Easily portable from computer to computer, so one purchase can be used at home, work, on the go without any hassle
- Uses standard USB cable so you can find lengths as necessary to drive your headphone even if your computer is far (htpc) or close (laptop)
- Sounds way better than onboard audio and most computer sound cards if not all
- Powers 300ohm headphones to ear splitting levels without the sound falling apart
- 96k/24bit support - finally listen to those hi-res recordings for real. The 96k/24bit support on most sound cards is....not worth even using hi-res.
Minuses
- Reports of high pitched tone reported by certain people. I can't hear it with any of my equipment but many have concern over the issue since it does afflict more than a few people (Update - The 2khz tone problem has been identified as an issue with a batch of ESS dac chips running with higher noise levels (but still within spec) compared to others. Nuforce has developed a correction and made a plan to fix all those affected. Essentially this is now a non-issue and Nuforce will take care of you)
- Volume imbalance and dynamics at low points of the knob still not ideal for the most sensitive IEMs unless you listen really loud.
- Heavy for the size - it's not that heavy really but it seems dense and if it falls on your foot it can hurt.
- Volume knob not as high quality as the rest of the unit
- Bug in usb chip firmware or something causing it to be recognized as a recording device
- The additional difficulty dealing with this device in ASIO4all in winXP. The previous minus point is probably a big cause of this problem.
-Updated 10-22-2010 - High Pitch tone issue resolution update
-Updated 10-8-2010 - Completed review
I'll continue posting updates for anything new I find as I continue using the unit.
Product: Nuforce uDac-2
A portable USB powered DAC with a built-in headphone amp. It also features a pair or RCA outputs controlled by the volume knob, and an SPDIF output.
Packaging:
Dimensions of packaging: 6" (7.1875" including hanger flap) x 6" x 1.375"
Nuforce has got the packaging retail ready. The uDac-2 comes in durable plastic box with a hang hole flap, the material is very thick and the box itself is unlikely to be damaged. You can see the device inside the box so a buyer can have a feel for the size of the unit. The back has specs of the device for those who may be comparing with other devices on the shelf. The box is rather plain otherwise, without the refinement a company like Sony or Monster Cable would otherwise embellish the packaging with. The box design looks a little generic, and on the shelf next to the big brands it would really give the feel of being one of those low cost Asian products without the budget to put into package design. However, functionally speaking I think it works well. The package looks the same after being used multiple times, with no creases, no ripped flaps, no torn paper from stickers...it essentially looks new.
Contents:
- uDac-2
- Instruction Manual
- 1 Meter ChingLung Hi-Speed USB 2.0 cable - AWM 2725 80 degree C VW-1 28AWG/1P and 24AWG/2C
The Manual doesn't have too much important info in it, the most pertinent being the specs and the warranty. The usb cable looks pretty decent. The warranty coverage is 1 year, and there is also a 30 day return period. It is known that Nuforce has no hassle with their 30 day return policy, if you don't like it you can return it for a full refund.
Product Details:
MSRP: $129
Dimensions of rectangular area: 2.67" x 1.65" x 0.83" (note: both the manual, box, and website have the dimensions wrong. I measured myself and got a far different depth)
Dimensions including all protrusions: 2.67" x 2.44" x 0.83"
Available Colors: Black, Silver, Red. Only the main body shell differs in color, the front and rear faceplates remain black.
Design:
- The body looks to be made of anodized aluminum with a matte finish.
- The body seems relatively scratch resistant and should pick up no noticeable wear when placed on normal surfaces it would come in contact with in daily listening use.
- I like the build quality better than many other audio equipment in this price range which is usually made of plastic. The unit seems very strong and solid. It feels quite heavy for the size, and shaking it around has no rattles of any kind.
- The Nuforce logo imprinted on the top and bottom of the case look nice, it is a stylish product overall.
- The connections are clearly labeled, the jacks are color coded as well. Red - right, White - left, Orange - coaxial digital out
- I wish it came with attachable rubber bumps of some sort. Being small and hard anodized aluminum, it tends to slide around a lot and will probably scratch your table.
- Visually it looks exactly the same as the original uDac. I see no way to visually tell them apart.
Volume Control:
- The knob is made of black plastic, the finish matches well with the aluminum finish, it doesn't look out of place.
- The knob is as large diameter as it can be due to the size of the uDac-2 itself. It's size makes it easy to make minute adjustments in volume and makes it easy to grip too.
- Off is 7:30 and full volume is 4:30. It clicks from off to on, then volume goes up.
- The volume knob on this unit is crooked, which you can obviously see when you turn it. One of the photos shows a view where you can see the angle of crookedness. I could not fix it by pressing on it but I didn't want to break it off. Hopefully this is not a common problem as it detracts from an otherwise high quality looking product.
- The uDac-2 is supposed to use a highly linear TOCOS volume control which is different than what is in the original uDac. It is supposed to track volume better between left and right especially at lower levels. I think I read that the volume ramp is also supposed to be more gentle so you can more easily control it at lower volumes and sensitive headphones than the uDac
- From my impressions when comparing this unit to a sample of the original uDac, I heard no obvious difference in tracking accuracy improvement. Both started off with one side slightly louder, raising the volume just a bit more on both of them match volumes up right away which is good. As you turn up the dial more, it seemed like the uDac-2 actually raised in volume at a slightly faster rate than the original uDac, counter to how I thought it was supposed to behave. Overall, I'd say the volume control of the two models don't differ very much. Of course there is always sample variation, but from the single samples of each model I can't say the volume control differed significantly. If the original uDac I had to compare with had one of the badly off ones I probably wouldn't be saying the same thing. Maybe on the average, the new volume control is more consistent in each unit matching volumes at low levels compared to the original one which had enough complaints where some units were really bad and some good enough. Whatever the case, the change was made to have a new volume control but my testing of it netted no obvious difference.
Inputs:
- Full size USB Type-B jack - The uDac2 only gets it's input as USB digital audio, it has no other inputs
- The uDac-2 supports 96khz 24bit usb audio, which is an improvement over the 48khz 16bit support of the original uDac.
- I like that it uses full size USB rather than mini or micro. The cable ends in this style are stronger, there are better cables available, and the jacks itself are probably less likely to break as well.
Outputs:
- Headphone out in the front - controlled by the volume knob, 1/8th inch jack
- RCA analog out pair in back - controlled by the volume knob, gold plated - This makes it possible to use this to drive an amp directly. If you want to use this as a line-out, you can just set the volume knob to 100%. It is a little hotter than many standard line-outs from other devices I tested, but still works fine without clipping my amps.
- RCA digital coaxial out in back - gold plated - I did not test this, but I believe it always outputs digital data now regardless of knob position. On the original uDac, the volume knob had to be set to off to have the coaxial send digital data. This jack can be used to get digital audio from your computer to your home theater receiver or higher performance DAC without a usb input. Since I haven't tested this feature in detail, I will just leave this as my only comment on this feature for now.
Crooked volume knob - The only build quality complaint
Usability:
- Most of the time the unit is great. Plug it into the computer, it becomes the default sound card, and sound goes through it.
- However, there are a couple of behavior differences when compared to the original uDac
1. The uDac does not let the windows volume control have any effect. The uDac-2 does change volume with the windows volume control. This means users must pay attention to make sure they have all volume controls related to the uDac-2 set at 100% if they want to get the best sound quality. This was not a worry with the original uDac. However, the advantage is people who have trouble trying to listen at lower volumes with highly sensitive IEMs can now do so by lowering the windows volume control and getting the volume pot out of that poor left-right tracking area.
2. A potential bug in the USB chip exists. In windows XP using asio4all, the uDac could be plugged in at any time after being setup once, and it would play in foobar. You could plug and unplug it all you want, and the next time you wanted to play, it would work. With the uDac-2, I believe there is a bug. I first noticed that after setting it up correctly (which took a while you'll see later), if the unit was unplugged and later plugged back in, it would not play and I had to go deal with the settings all over again. In fact, it was very difficult to setup the first time in asio4all. The problem is that the uDac-2 exposes an input pin like a recording device, but the uDac-2 cannot record. In asio4all you have to make sure you disable that pin and only enable the stereo output pin in order for it to work. This necessary step I'm sure messes up many people trying to use XP with asio4all and foobar.
I also think it's a bug because in OSX, the uDac-2 shows up both as an audio playback device and a recording device as well. Obviously the uDac-2 cannot record as it has no inputs.
3. The uDac could only play up to 48khz 16bit, the new chip can play up to 96khz at 24bit now. This gives you the ability to play hi-res recordings that are getting more common these days.
4. The iPad can support the original uDac through the USB camera kit from what I've read. However, the uDac-2 does not work on the iPad afaik.
Sound Comparison Setup:
To compare sound, I will test the uDac-2 against two other systems also capable of 96/24 playback and with a variety of headphones.
In Win7: Foobar -> Wasapi -> to.....
A. Nuforce uDac-2 with bundled usb cable - has a Sabre 9022 DAC and the advertised capability to support 16-300 ohm headphones.
B. Creative Labs X-Fi Fatal1ty Professional Series PCI sound card in audio creation mode, all DSP's off, bit matched playback, through Belkin 2M 1/8th extension (sorry, can't reach the jack comfortably for testing without the extension)
C. Nuforce HDP with Wireworld Starlight 1M usb cable powered through Pangea AC-9 powercord with stock power supply. For IEM tests, sound comes out of RCA jacks with volume pot at max volume with Nuforce 1.5M Transient RCA to 3.5mm cable into Pico Slim. The reason is I can't listen to HDP through any IEMs directly because the hiss and volume level is overpowering for me.
Giving relative sound among these 3 systems may help users place where the uDac-2 performs with specific headphones and music. System B is a very common sound card series (X-Fi) and gives a basic representation of a standard sound card audio. System C is quite a nice DAC/AMP that works well with a computer through USB. The uDac-2 can play anything these 2 systems can play out of a computer so it'll make for some good comparison testing.
Sound with different Headphones:
Shure SE530 - triple balanced armature, 18hz-19khz, 36 ohm impedance (@1khz), 119db/mw (1mw)
It's been a while since I've used this headphone, I don't remember this headphone being so bass light. Weird, I used to think this headphone had lots of bass, but I did come from an E4 when I went to the SE530. Anyway this headphone is one of my most sensitive pairs and at 36 ohm should be pretty easy to drive. However, this sensitivity also becomes its achilles heel when used with the uDac-2.
The first problem using this headphone with the uDac-2 has a clearly audible hiss with this headphone is plugged in. The hiss is louder than what you can hear when plugged into the X-Fi, where the X-Fi has a lower pitched and softer hiss, the uDac-2 has more energy in the hiss in the higher frequencies so it is more bothersome. With the HDP headphone out the hiss is so significant that I can't use it and thus have to test through the Pico Slim, which I hear no hiss at all in this comparison. With lots of music, I can hear the background hiss with the uDac-2 and it ruins the effect of a clean acoustic performance, or a silent concert hall, etc... Basically when you want pure blackness between notes, you don't get it with the SE530 paired with the uDac-2. To get a relative volume of the hiss, the uDac-2 hiss is significantly softer than the HDP headphone out, is softer than the hiss of the ipod video (5g), is louder than the hiss of the iphone 4 and 3gs, and is louder than the hiss of the X-Fi,
The second problem using this headphone with the uDac-2 is by the time the volume control equalizes both channels to be equivalent, for much music it is much too loud for my ears. For comparison, the X-Fi has no sound until the volume control hits 5, I can listen to many albums at this level, it is a good level. On this headphone, the sound on the uDac-2 equalizes at a level that is about 8 on the X-Fi. This is decent for many softer recordings but way too loud for many modern hip hop, pop, rock recordings. It will just blow my ears off trying to listen. For reference, this position on the uDac-2 dial is about 8-8:30.
On to actual sound comparisons. This is one of the headphones that I was thinking would show less difference between amps/sources being it is easy to drive and is so bass light and treble light that it would kind of mellow out and make things sound similar. However, I was surprised at the amount of difference between the 3 systems with the SE530. One of the first things noticed about the X-Fi is how poor the sound simply is compared to the uDac-2. You get an immediate improvement in clarity, all instruments sound more clear instead of blurry and veiled on the X-Fi. You also get a soundstage instead of what seems like no soundstage at all in comparison with the X-Fi. For example, when hearing a singer who is performing front and center, on the X-Fi you hear the singer and it is a wall of sound. With the uDac-2, the singer is focused and it sounds more like a person singing in front of you rather than 2 poorly placed speakers just broadcasting the singers voice. I don't know what the X-Fi does wrong to make it sound so diffuse, but the uDac-2 is a clear improvement in this area. However, compared to the HDP system, it is clear the uDac-2 is still far from perfect. The HDP gains much more focus and soundstage. However, I'd say the difference in focus and soundstage is much greater between the uDac-2 and X-Fi than it is between the HDP and uDac-2.
The bass on the se530 seem weak, but this is especially so when driven directly by the X-Fi. Where the X-Fi makes bass seem to not exist in certain songs where there are deep sustained notes, the uDac-2 makes it audible. The X-Fi kind of slides into the beginning of it, but dies down where the uDac-2 can sustain the note. This makes dance music with the boom boom boom much nicer to listen to. However, the uDac-2 bass still seems out of control with the SE530 somehow. You can hear it better, it is stronger, but is better in every way compared to the X-Fi, but it still feels sloppy. This is most evident once compared with the HDP system which has tight control over the bass. Where the uDac-2 seems to swell at bass hits, it doesn't have snap like the HDP. When the bass note transitions, it is slow with the uDac-2, tight with the HDP system, and nearly non-existent with the X-Fi. In one song, with the X-Fi, I could hear some bass notes that transitioned with the song, but it just sounded like a single bass note that was held and changed pitch at different times. With the uDac-2, you finally feel some texture to the sound, you know it's coming from an instrument now and it's not just a synthesized note. However, it is not until the HDP that you realize it is a bass being plucked for each note. I don't know if the HDP Dac is so much better than the uDac-2, or if it is the pico slim is a much better amplifier for the SE530 than the uDac-2. But it is obvious the uDac-2 is not at the level of the HDP. On the bass performance with this headphone I'd say the HDP system is about as much an improvement over the uDac-2 as the uDac-2 is over the X-Fi.
Now on to transient performance. When I first listened to the X-Fi with cymbal hits in music, it didn't sound like a cymbal much. It sounded like a millimeter thick felt pad laid on top of a cymbal and then hit with the stick. The sound had no attack, it had no clear ringing that you'd expect. The uDac-2 improves this quite a bit so you get a crisper hit. The same applies to the attack of the initial bowing sound of a stringed instrument like a Cello, that initial bite is lost with the X-Fi but can be heard with the uDac-2. Without that bite, you lose the rhythm, pace, and timing which that bite of the bow hairs into the string brings. The uDac-2 is much more exciting to listen to than the X-Fi when Yo-Yo ma plays aggressively with his Cello. You can feel the emotion of his playing that is lost with the smear of transients by the X-Fi. The HDP resolves more detail in the bite than the uDac-2 though, but the uDac-2 already makes things much more enjoyable than the X-Fi. The same goes for piano, the X-Fi smears it so it sounds like a synthesized keyboard and not a good one either. However, for piano the improvement with the uDac-2 is noticeable but less than the improvement the HDP brings to the piano. On the HDP where you can tell the percussive nature of the piano with the sharp attack of the initial note being struck and the sound of the decay, the uDac-2 rounds the attack a bit. But this is still bounds better than the X-Fi FM synthesized sound like piano that comes out. Again, this brings up whether the improvement in transient performance is a result of the amp having a hard time with the SE530 load, or the DAC in the HDP is really that much better. Maybe I'll have more to say as I move on to other headphones.
Where the X-Fi veils everything, blurs transients, mushes up fast instruments, has a blurry unfocused soundstage and gets congested all the time with complex music, the uDac-2 improves upon that. All sound is clearer, there actually is a soundstage now, instruments sound more like real instruments. However, at the same time it is also clear when hearing the HDP system that there is still lots of improvement available in these areas and the uDac-2 is not a holy grail of computer music playback, at least not with the SE530. So universally the uDac-2 is an improvement in almost every way to the X-Fi when paired with the SE530 except for 2 areas, excessive hiss and difficulty with using at lower volumes due to channel matching. But I believe there are many people who won't hear the hiss with this combination and will actually be playing well above the point of volume matching. I know my ears are on the sensitive side and I play at much lower volumes. At $129 which is about the price of the X-Fi, the uDac-2 is a much preferable device for music playback with the SE530 if you are one who does not have issue with the hiss or need to use below 9 o'clock on the volume dial. However, for someone like myself, I cannot recommend the uDac-2 with the SE530 as the hiss detracts too much from the experience, and some of my music is unlistenable due to high volumes.
Shure SRH840 - closed back full size, 44 ohm impedance (1khz), 102db/mw (1khz), 5hz-25khz
Grado RS1 - open air full size, 32 ohm impedance, 98db/1mv, 12hz-30khz
I put these two headphones together because the sound differences using the different sources was very similar. First, the differences are dramatically less between the sources using these two headphones than the SE530. This actually surprised me quite a bit as I expected the SE530 to be one of the headphones that you'd be able to tell less difference between the sources. First of all, there was no detectable hiss using these two headphones with the uDac-2...at least not in the not completely quiet environment I had to work with. And the sensitivity levels of these two headphones allows a good degree of control over volume which I did not have with the SE530. So basically there is no problem with the music being too loud and not having the ability to turn it down when using these two headphones. However, you still can't listen to louder music very very quietly or you'll hit the imbalance issue again, but it will be at moderate and comfortable volume.
The 3 sources had much closer bass response with these 2 headphones. The difference wasn't as dramatic as the SE530. In terms of control, the HDP still wins, but the uDac-2 seems to produce more bass overall than the other two. The difference is not so drastic, and the X-Fi is able to do pretty good with the bass as well. This time the bass is not vanishing with the X-Fi the way it was before. However, the definition in the uDac-2 is still greater than the X-Fi and still better again going to the HDP. However, it is not as noticeable compared to the SE530.
Much of the obvious sound transient differences are also gone when using these two headphones. First, cymbal hits on the X-Fi actually sound decent now. The improvement going to the uDac-2 is slight, and moving to the HDP again is only slight again. The difference is more in the detail of the resonance after the initial strike. Where the X-Fi seems to have little detail, the uDac-2 shows more detail, and again the HDP shows a bit more. However this time the difference is the uDac-2 is much closer to HDP performance than X-Fi. The same trend holds for drum snaps, guitar plucks, hand claps. The X-Fi is able to do much better now, and the improvement going to the uDac-2 is less, and even less when moving to the HDP this time. Overall though, the uDac-2 is closer to the HDP than the X-Fi in this regard. This is a good sign for the uDac-2.
So with a lot of the obvious things with sound characteristics that can be picked up with a quick listen much less obvious now, what is really different between the 3 sources? Well for starters, one is detail. Though you might feel similar bass punch and rumble using all 3, and similar clear cymbal hits and guitar plucks....the detail in the sound is significantly improved by the uDac-2 over the X-Fi. The X-Fi makes the sound, but the uDac-2 adds texture to make it more real. The HDP is not much ahead of the uDac-2 the way the uDac-2 is leaps ahead of the X-Fi in detail retrieval. While the X-Fi no longer sounds like it veils everything and sounds ok at first listen, once you compare it to the uDac-2 you notice it is much more of a flat sound without the detail that makes it sound like a real instrument. Some other aspects still remain true like before, the soundstage of the uDac-2 is much better than the X-Fi. With the HDP it is only slightly better than the uDac-2.
These two headphones must be much easier to drive for the X-Fi to sound so much closer to the other two sources. However, without any drawbacks of hiss and sensitivity issues when using these two headphones, I can definitely recommend getting the uDac-2 with these headphones. You are getting closer to the performance of the HDP and making music much more enjoyable than on the X-Fi. I think the differences heard now are the differences between the different DACs...the detail, soundstage, and presentation. With the SE530, I think the differences were the different amps handling capability of the IEM resulting in extremely different performance.
-Sennheiser HD800 - open air, 300 ohm impedance, 102db @ (1khz/1V rms), 15hz-44.1khz (-3db)
This is my main headphone and after listening to it again it is obvious why the Shure and Grado showed much less differences between sources than I would have expected. They just overall had less detail than what I normally hear out of the HD800. So with a reference headphone how do the 3 sources sound? Well one thing I learned is that even through an X-Fi sound card, the HD800 can sound pretty decent. However, with this headphone it also shows more apparent differences between the three sources.
Strangely, at least for my listening limits, all 3 sources easily got loud enough. In fact, at least based on the volume dial travel position, the uDac-2 seemed like it was louder at a lower volume setting than the HDP. That doesn't really mean the uDac-2 can get louder though, as who knows how the volume taper works out for the rest of the dial. However I wasn't about to blow my ears to try it out. Now what happens as you start raising the volume is the X-Fi starts to sound honky. It seems to be due to lack of drive power as it only happens at higher volumes, it seems to throw all sorts of artifacts into the sound. It makes it very painful to listen to loudly. With the uDac-2 and HDP however, both are able to scale up in volume cleanly and continue sounding good at the limits of my capability before it is to painful to keep it on.
When it comes to bass slam and deepness, the X-Fi has trouble delivering any slam, and maintaining sustained deep bass notes. The uDac-2 improves on the slam and power greatly, but seems to lack the texture in the bass the HDP brings. The HDP also improves the bass slam to a level above the uDac-2. However, it is clear the uDac-2 and HDP are well above the level of the X-Fi, especially as volume is raised and you want to feel the power. If you like it loud and clear with the HD800, the uDac-2 does plenty well in this arena compared to the X-Fi.
Though many instruments sound clear and sparkly with the X-Fi and HD800, voices in particular sound muffled for some reason. This is very apparent as you move to the uDac-2 how much singing voices clear up. Maybe it's the fact that we know how human voices are supposed to sound that any unnaturalness due to poor dac or amp performance become dramatically clear. Again, the HDP can improve upon the uDac-2 even more in this regard as voices gain more openness and detail but this seemed only apparent with the HD800. The other two full size headphones I did not have this impression.
The HD800 soundstages very well, and this is an area where you hear the X-Fi do a poor job compared to how well the uDac-2 performs. The uDac-2 presents a good soundstage with distinct placement of all instruments and singers, you can sense where everything is. In fact the uDac-2 does so much better when you switch to the X-Fi you think there is something wrong as the soundstage just collapses. Or maybe I should say all the instruments lose focus and blur together, that is really the effect I feel. Yes, the uDac-2 still gives up the precision the HDP has in placing sounds within the sound field, but it does so much a better job than the X-Fi.
When it comes to detail, the differences become very apparent with the HD800. When you move from the X-Fi to the uDac-2, it goes from a veiled like sound to clear sound. Violins that sound monotone and not really like stringed instruments on the X-Fi actually sound like violin with additional note emphasis and stringing detail on the uDac-2. Trumpets that have a smooth tone on the X-Fi have texture on the uDac-2. The difference is pretty dramatic in everything you listen to, the X-Fi is not a source you really want the revealing hd800 paired up with as you are not hearing so much that is in the recording. The HDP does trump the uDac-2 again as now as not just can you hear additional detail in the trumpet, you can hear the breath sounds and the initial push of air the player is doing on this one piece I was listening for. Initially hearing it on the uDac-2 I wasn't sure what it was but once heard with the HDP you can imagine exactly what that sound is.
Without going further into what is obvious now, the uDac-2 is a major step up with the HD800 compared to the X-Fi. And with the HDP, you get another big step up in performance over the uDac-2 which is more obvious with something as detailed and with such an open soundstage as the HD800.
Conclusion
I think the uDac-2 at $129 is one of the best bang for the buck values I've encountered. Well, maybe other than the original uDac which at $99 was an even better value if the sound is the same. But I never got to extensively listen to it to see if it was at the level of quality the uDac-2 is. However, the uDac is no longer available so that is moot point. Right now it will probably be hard to find something with this combination of features, build quality, and sound quality at such a price point. In fact, I can't think of another device near this price that I could recommend to friends who want to get into the path of an audiophile at an affordable price point. Just being a usb DAC/headphone amp at this price would be enough for me to recommend it, but this also has RCA line-out and coaxial digital out if you want to get computer audio to a home theater receiver digitally. Those are bonuses if you're one to find uses for those features.
The build quality is also amazing at this price point. Usually you find light plastic boxes with mini-jacks and sliding volume controls. Or maybe a usb stick sized device with a single shared input/output optical mini-jack port and the susceptibility to be snapped off if used on a laptop without care. In any case, this device looks like it will last a long time, coming with a durable full size usb jack, very solid RCA jacks, a supposedly high quality volume pot, and a thick anodized aluminum case. Plus, it looks pretty cool, who is to imagine such good sound comes from such a little box. I think it'll surprise a lot of people who haven't heard higher end audio before and are only used to computer sound. This device will up their quality quite a bit if they have good headphones to pair with it.
From a lot of the sound comments above, it may seem like the sound isn't that great with the HDP obviously being better. But do remember I am comparing this $129 product with a $449 product from the same company. That is a very different price range we are looking at and it was only used as a reference to see how far it can keep up in sound to something significantly more expensive. In overall sound, the HDP is still significantly better in my opinion. However one place where I find the uDac-2 better than the HDP is using with very sensitive IEMs. The hiss level is much more manageable on the uDac-2 than the HDP, though I feel neither do justice to sensitive IEMs the way the pico slim hooked through the HDP handled it. Maybe it's the fact that both were near the very beginning of their volume travel and they felt less dynamic and clear than the pico slim when driving the SE530. Compared to the X-Fi though, the uDac-2 is still a huge upgrade when using IEMs and if that is all your budget allows, I say go for it.
So my final word is if you want good sound below $150, the uDac-2 is a great way to get it! I actually have no better product to recommend to friends just getting into audio and don't want to spend too much.
Pluses
- Small and Durable build making it very solid and unlikely to be damaged if thrown into a bag with a bunch of other stuff
- Easily portable from computer to computer, so one purchase can be used at home, work, on the go without any hassle
- Uses standard USB cable so you can find lengths as necessary to drive your headphone even if your computer is far (htpc) or close (laptop)
- Sounds way better than onboard audio and most computer sound cards if not all
- Powers 300ohm headphones to ear splitting levels without the sound falling apart
- 96k/24bit support - finally listen to those hi-res recordings for real. The 96k/24bit support on most sound cards is....not worth even using hi-res.
Minuses
- Reports of high pitched tone reported by certain people. I can't hear it with any of my equipment but many have concern over the issue since it does afflict more than a few people (Update - The 2khz tone problem has been identified as an issue with a batch of ESS dac chips running with higher noise levels (but still within spec) compared to others. Nuforce has developed a correction and made a plan to fix all those affected. Essentially this is now a non-issue and Nuforce will take care of you)
- Volume imbalance and dynamics at low points of the knob still not ideal for the most sensitive IEMs unless you listen really loud.
- Heavy for the size - it's not that heavy really but it seems dense and if it falls on your foot it can hurt.
- Volume knob not as high quality as the rest of the unit
- Bug in usb chip firmware or something causing it to be recognized as a recording device
- The additional difficulty dealing with this device in ASIO4all in winXP. The previous minus point is probably a big cause of this problem.
-Updated 10-22-2010 - High Pitch tone issue resolution update
-Updated 10-8-2010 - Completed review
I'll continue posting updates for anything new I find as I continue using the unit.
