project86
Headphoneus Supremus
- Joined
- Feb 21, 2007
- Posts
- 7,804
- Likes
- 4,376
[size=small]Not long ago I reviewed the new DAC-100 from NuForce. I was impressed with its dynamic, exciting sound, which focused more on musicality than excruciating detail. Fast forward a few months, I also covered some of the matching Home Series gear over at InnerFidelity[/size][size=small]. I liked the whole lot of it, which was not something I had anticipated. But I did have a few minor complaints. Specifically, I noted the DAC-100 didn't have the same design aesthetic as the rest of the group. As a higher priced model I guess it made sense to have a standout enclosure made of higher quality materials, but it still seemed odd that a person using the DAC-100 with the HAP-100 headphone amplifier would have a stack that didn't quite match. It's close, but not exact. The other issue was regarding duplicated features - the DAC-100 user got a very credible integrated headphone amp, which I could see negating the need for the stand alone HAP-100 unit. I suppose that could be considered good for the consumer and bad for NuForce, but personally I think the target market for nice DAC like this would eventually be after a stand alone amp anyway. I remain torn about integrated amplifiers in higher end DACs - at times they seem like a brilliant idea (assuming they are of decent quality) and other times the feel like an unnecessary expense that will end up not being used. I'm sure readers have their own opinions on the matter which help shape their potential purchasing choices.[/size]
[size=small] [/size]
[size=small] Not long after that review, I was informed that NuForce (abruptly?) discontinued the DAC-100 and replaced it with their new DAC-80 model. Essentially the DAC-100 minus headphone section, the DAC-80 uses the familiar Home Series enclosure and sells for $795, which is $300 less than the 100. This made some sense to me so I asked them if I could give it a try to compare with the original. [/size]
[size=small] [/size]
[size=small] DESIGN[/size]
[size=small] The DAC-80 is very similar to the original DAC-100. It's got the same overbuilt power supply with Noratel brand toroidal transformer and extensive array of capacitors and voltage regulation. It's got the same AKM AK4118 digital receiver, the same Nuforce branded USB implementation capable of 24/192 operation, and the same AKM AK4390 32-bit DAC. It also has the Xilinx FPGA doing who-knows-what to help eliminate jitter. The one difference that jumps right out is the output stage - it uses the same pair LM4562 opamps but has no transistor buffer. The DAC-100 had heatsinks packed tightly and the DAC-80 just as an empty spot in that location. As far as I can tell the actual PCB is the same in both models with the DAC-80 losing that part of the output stage plus a few minor changes like different capacitors. Even the USB board still says "DAC-100" on it. [/size]
[size=small] [/size]
[size=small] The DAC-100 uses a somewhat unique configuration where it drove the headphone stage with one channel from each LM4562 and buffered that with transistors running in class A. The line output used the "other half" of that - which explains why they needed a pair of stereo opamps for a single ended design. The DAC-80 no longer needs to power headphones so it actually could have used a single stereo opamp, but it was likely easier for NuForce to keep things as-is. There's probably also some potential for reduced crosstalk by running each channel from a separate opamp. [/size]
[size=small] [/size]
[size=small] All this time I was operating under the assumption that the DAC-100 used transistors for both the headphone amp and the line-out stage. But maybe I was wrong - maybe the class-A transistor section was entirely used by the headphone stage, and the line-out was purely opamp based. That's certainly possible and either way it shouldn't take anything away from the excellent performance of that unit. As I read the datasheet for the AK4390 I notice it does voltage output rather than current output. So there's no I/V conversion stage needed. The LM4562 operates as an LPF and the output we get is basically straight from the DAC chip itself. Since the FPGA handles jitter rejection, there's no upsampling scheme involved, which means a very pure signal goes straight from the DAC chip to your amplifier of choice. [/size]
[size=small] [/size]
[size=small] [/size]
[size=small] As you can see, the front and rear panels are pretty much the same as the DAC-100:[/size]
[size=small]
Internally, everything remains the same was well - power supply filtering:
Noratel toroid:
Another view of the 17 caps:
Overall interior - can you spot the one difference from the DAC-100?
This lettering is the same:
Same Xininx FPGA and same PIC microcontroller:
Same AKM digital receiver:
This is the actual DAC chip itself. Looks like NuForce tried to obscure the text, but
I can still read it in certain lighting. Not sure why they hide it - it's a quality modern chip:
The USB section even says DAC-100 on it:
LM4962 opamps... getting warmer as far as what's different:
Bingo! There it is! Big empty spot where the output transistors and heatsinks used to be
in the DAC-100:
[/size]
[size=small] [/size]
[size=small] [/size]
[size=small] FEATURES[/size]
[size=small] Again, just like the DAC-100, the DAC-80 is a DAC with preamp functionality thanks to its 32-bit volume control implementation. With inputs including asynchronous USB, Toslink, and coaxial SPDIF (x2, transformer isolated), and the included remote, the unit could in fact be a viable preamp for a small system (obviously using digital sources only). With the integrated amp no longer on board, and matching casework this time around, the HAP-100 seems like an obvious dance partner for the DAC-80. [/size]
[size=small] [/size]
[size=small] The front panel is visibly different from the 100 but functionally very similar. Instead of dedicated buttons for source selection, the 80 borrows ideas from the rest of its Home Series cousins - push the volume knob to cycle through sources, hold it down to enter or exit standby mode. There's an actual power on/off switch on back. Same rate indicators remain in place, looking close but not quite identical to the 100.[/size]
[size=small] [/size]
[size=small]
[/size]
[size=small] [/size]
[size=small] SOUND[/size]
[size=small] After giving it extensive time for burn-in, I set out to give the DAC-80 a listen. Rather than start from scratch, I began with the assumption that the 80 should sound at least roughly similar to the 100. So my initial testing was centered around direct comparisons between the two. If the 80 ended up sounding vastly different, I could then start over and get a feel for it all by itself.[/size]
[size=small] [/size]
[size=small] Thankfully for me (since the alternative would be more complicated) my initial assumption proved correct. Despite the simplified output stage which no longer has the discrete buffer, I can't reliably tell the 80 apart from the 100. There were times when I actually thought the DAC-80 was ever so slightly better than the 100 - by just a hair - but these were fleeting. So ultimately I'd say they are close enough to be indistinguishable. [/size]
[size=small] [/size]
[size=small] This supports my new theory that the 100 used the discrete buffer for headphone duties only. So all this time I was listening to (and enjoying!) a more simple design than I had thought. But that's fine with me - designers should be building around their chosen architecture rather than adding stuff just for the sake of complexity. When the chosen parts call for simplistic design - and the AK4390 appears to do just that - then I'm all for it. [/size]
[size=small] [/size]
[size=small] You can read my DAC-100 review to hear more about my impressions of the sound. In a nutshell, it's a somewhat musical sounding DAC, very dynamic and exciting. Definitely a different sound compared to the recent trend of hyper-detailed DACs. Not that detail is poor - in fact top end air and extension is on the strong side, but it's refined enough to avoid that "digital" feel. I particularly like it paired with my Analog Design Labs and Icon Audio single-ended triode amps. I can use different DACs and amps to assemble a more detailed system, or one that does better vocals, or one with more finesse. But for sheer musical, toe-tappin' fun, the NuForce/SET amp combos are tough to beat. And I don't mean that in a disparaging way, where the sound is slow, syrupy, murky... It remains fairly balanced for the most part - it's just got some extra excitement there compared to more neutral options. [/size]
[size=small] [/size]
[size=small] One of my chief questions, the reason I was interested in evaluating the DAC-80 in the first place, was to see what amp I could pair it with in order to match the DAC-100. As an all in one design, I thought the DAC-100 was a great value and an exceptional match with the HD800 and T1. The 80 costs $300 less - what can we get for that price in terms of stand alone amplification? The list of potential suspects is not huge - the Matrix M-Stage is really the only one I currently have that doesn't exceed the $300 difference. The Lake People G103 (in standard form, not the Pro version with XLR) squeaks in at less than $300, but I sent mine to Tyll Hertsens for measurements so I don't have it available right now. I decided to stretch things a bit and include the Yulong A100 which exceeds the budget by $60 or so depending on who you buy from. And then of course I had to try the DAC-80 paired with the HAP-100 which combined sells for $300 more than the DAC-100 alone. [/size]
[size=small] [/size]
[size=small] The DAC-80 plus Matrix M-Stage is actually a really great combo. I'm currently running the M-Stage with the class A biased OPA627 opamps - there may be some better opamp choices out there, but this one is pretty darn good already, and is available from Tam Audio around my target budget for this comparison. I had loaned out my M-Stage for a long time and when it recently came back, I was surprised at how well it holds up. I think overall the DAC-80/M-Stage combo is a better performer than the DAC-100 alone, with a few caveats. The M-Stage brings to the table a quieter background and a more seductive midrange. This is welcome with some headphones like LCD-2 and Denon D7000 where the DAC-100 could sometimes feel a little distant with vocals. To some degree the effect remains, no doubt due to the character of the DAC itself, but the M-Stage seems to mitigate it compared to the integrated amp section. But when I switch to the HD800, a headphone known to pair well with the M-Stage, the integrated amp still pulls ahead. There's just a synergy thing going on where I really enjoy it. The Beyerdynamic T1 also seems to do better from the DAC-100, with a smoother and more controlled top end and better bass extension. Overall I'd say the M-Stage wins more often than not, but when the DAC-100 shines it really shines brightly. [/size]
[size=small] [/size]
[size=small] Next I switched to the Yulong A100 which sells for roughly $360. The A100 is a killer budget amp, very detailed and clean. With the DAC-80, the result is again very good with a wide variety of headphones. But this time around it's a little more thin and tilted towards the top end, so doesn't go as well with the K701 or the Audio Technica models that are already somewhat bright and/or bass shy. With HD650 or Denon headphones, the A100 is exceptional and definitely improved over the DAC-100 - tonal balanced ends up being similar but detail and clarity are superior. But again the HD800 and T1 do best with the integrated unit. A minor thing, but the A100 doesn't stack well with the DAC-80, as it's deeper than it is wide (and the NuForce is the other way around). In the end my preference shifted based on my mood - do I want more detail and accuracy, or am I in the mood to rock out? [/size]
[size=small] [/size]
[size=small] Finally, NuForce's own HAP-100. Remember, this combo is $300 more than the DAC-100. I notice a significant improvement in the low bass region, with more believable grunt and extension. I notice superior imaging and accuracy in the soundstage. And those vocals, which had been slightly recessed at times, were almost as forward as I'd like. That last bit is tied with the DAC character and will never go away completely, but the HAP-100 is one of the best I've heard for bringing those mids forward. [/size]
[size=small] [/size]
[size=small] The HAP-100 also seems more comfortable with planar headphones. Not that the DAC-100 is terrible on its own, but the dedicated amp seems to have more oomph (to use the scientific term). Mostly this shows up in the extreme low frequencies, which real instruments don't actually make. It just feels more solid. I can make either unit gracefully clip if I play music loud enough but the HAP-100 holds out longer before going there.... not that either really has an issue at normal volumes.[/size]
[size=small] [/size]
[size=small] By far the largest improvement comes with respect to noise floor. My biggest complaint about the DAC-100 was that it didn't really work so well on more sensitive headphones or any IEMs. There was a clearly audible hiss that not only appeared with my CIEMs (which is fairly common with desktop amps) but also with full sized headphones like the Ultrasone Signature Pro or Grados. I'm not talking about some vague noise floor issue - it's an actual hiss, loud and clear and highly obtrusive with certain music. As much as I like the DAC-100, it's basically off limits to those certain headphones. The HAP-100 brings a silent background to the table, even quieter than the A100 and M-Stage. This means significant gains in low level resolution, which leads to a more believable presentation. Custom IEMs like the Frogbeats C4, Heir 6.A LE, or the JH13 Freqphase are excellent at resolving those little details, so the improvement is very much appreciated. [/size]
[size=small] [/size]
[size=small] I also used the DAC-80 in my speaker rig with the matching STA-100 amp. It makes perfect sense in that application because speaker users won't necessarily care about the integrated headphone amp being removed. You still get the same high-quality DAC performance, the same well implemented 32-bit digital volume control with remote capability, and this time you get perfectly matching aesthetics. Add the HAP-100 for headphone capability and multiple analog inputs, and you've got a formidable stack for $2,000 that has great headphone amplification, truly versatile preamp capabilities with all sorts of inputs (digital and analog), and plenty of power for most speakers. The DAC-100 really wouldn't add a thing to that equation, so I can see why NuForce went in this direction instead.[/size]
[size=small] [/size]
[size=small] CONCLUSION[/size]
[size=small] The DAC-100 was discussed in the most recent HeadFi gear guide as being one of the best sounding DACs under $1500. I've heard a lot of DACs in that range and I'd have to agree - the DAC-100 is certainly up there on my list. And yet NuForce already discontinued that model. Why? Simple really - the DAC-80 makes more sense. It better matches the rest of the home series components in both price and appearance, and helps make a better case for the HAP-100 as a complimentary add-on. Oh, and it loses none of the rich, dynamic sound that made the original model so enjoyable. [/size]
[size=small] [/size]
[size=small] Will the integrated amp in the DAC-100 be missed? With HD800 and T1, absolutely. Those made for dynamite combos straight from the DAC-100, and for users of those headphones I'd say check around for remaining DAC-100 stock. For most everyone else, the DAC-80 is the way to go, and I completely understand why NuForce made the switch. [/size]
[size=small] [/size]
[size=small] [/size]
