Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › [Review] Nuforce HA-200 - affordable class-A monoblocks
New Posts  All Forums:Forum Nav:

[Review] Nuforce HA-200 - affordable class-A monoblocks

post #1 of 148
Thread Starter 

What is it?


A thing that makes the music louder

Class A, single ended, BUT two units may be configured as monoblocks for balanced operation

Constant-Current Output



The specs (Click to show)

From the website: https://nuforce.com/index.php?option=com_k2&view=item&id=678:ha-200&Itemid=2710


  • Frequency Response : 20Hz - 20kHz, -0.1dB, 300 Ohm load
  • Recommended Headphone impedance: 32 to 600 Ohm
  • Output Voltage and power (RMS): 1kHz **16 Ohm, 2.8Vrms, 0.5Wrms 30 Ohm, 5.6Vrms, 1Wrms **300 Ohm, 8.3Vrms, 0.22Wrms High Z, 8Vrms
  • Balanced Mode: 200 Ohm, 14.6Vrms
  • Maximum Output: 2W @ 32 Ohm, Balanced mode 8W @ 64 Ohm
  • THD + N: 0.002%, om 20-20kHz, 1kHz, 1Vrms
  • SNR: >120dB, weighted 2Vrms
  • System gain: 10dB
  • Input impedance: 22 kOhm
  • Output impedance: 5 Ohm
  • Power Consumption: 22W
  • Weight: 5 lb. (2.26 kg)


So why monoblocks? Is it for the cool factor? The increased power? For the reduced crosstalk? The separate power supplies and circuitry for each channel? Or perhaps we just do it because we can. I don't question my motivations in this hobby very much anymore beyond "I just want it".




Intro where I talk too much


While monoblock amps in the speaker world are nothing new, there are only a handful of choices in the head-fi world. In fact, as far as I know there are currently only three options:


Nuforce HA-200 - msrp $350 each ($700/pair)

Questyle CMA800R - msrp $1700 each ($3400/pair)

Woo Audio WA234 - msrp $15900/pair


I have not heard the Questyle or Woo, but with roughly a 5x price difference and vastly different topologies between each, direct comparisons may be moot anyways.


So let me tell you a little bit about the HA-200. It's the latest in their desktop series which all share the same chassis dimensions. I've owned several other components in the home series and the fit and finish is excellent as usual. Actually, the finish of the case is improved and more resistant to scuffs* and marks. The amp has a good heft to it and if you pop it open you'll see the big transformer, power supply, and ample heat sinking. Pricewise, it's also the cheapest in their home lineup (for a single unit).


a note on the scuffing (Click to show)


Actually on the old cases, the surfaces had a texture which was very resistant to scratching, but was hard enough that if you scratched your nails across it (such as when moving the amp or adjusting the volume), it would actually leave grind the nail and leave a trail. The surface is fine and it wipes off no problem, but it still a bit unsightly. The new chassis feels a bit smoother and doesn't grind your nails, so is more resistant in that sense to the scuffs.


So... double the price, is it double the performance? You know what... I'm just going to say yes on that one. A single HA-200 is fine on its own, but in balanced mode is where the magic happens. My only gripe is that it takes up a lot of desktop real estate and there's enough heat I don't feel comfortable stacking other components on top. (I'm sure it's fine, and I've measured it, but I just get ocd about stuff like that)


The power indicator is a tiny tiny red illuminated dot on the front panel. You know how most people complain that the LEDs are too bright? I actually wish they were brighter here as I can barely see them unless I'm at the right angle. It might be moot since I usually just leave the amp on, but still.


In a bit of a frustrating setup, Nuforce does not actually have a balanced source in their home series. You have to step up to their reference series in the DAC-9 to get that. Here's hoping that they actually release a matching balanced dac in the sub1k category sometime in the future.




The HA-200 is an amp that can serve in two functions. A single HA-200 unit acts as a normal single-ended headphone amplifier when you feed the RCA inputs, but pair it up with a second unit and it serves as a “balanced” (technically “bridged”) amp when you feed the XLR inputs. In single ended usage it you use the 1/4” TRS jack in front. In balanced mode you use the 3-pin XLR(f) on the front panel; thus your headphones will need to be wired with a dual XLR3(m) and/or make the appropriate adapter (Nuforce does not currently plan to make cables for the HA-200). The balanced and single ended modes should not be used simultaneously and as far as I know there is no protection circuitry there to stop you from doing something stupid.


Peering into the case and looking at the innards, it's not too hard to discern the main components of the amp. An OPA2134 opamp serves as a gain stage, and on each side you'll see a IRF510 and LM317 which by my best edumacated guesstimation is the mosfet as current buffer biased into class A by the voltage regulator.


Overall gain of the amp is 10dB (or 3.2x voltage). Not a very high gain overall, but really sufficient for most cans. Given that this is a pure headphone amp though, I do wish that there could have been a gain switch somewhere (or even a jumper inside) to make it more flexible. But switches and adjustable things add to the complexity, and sometimes pure and simple is better.



Having looked at similar DIY options before, and knowing the HA-200 puts out 10dB of gain, I could make my second educated guess of opamp gain x4 with a mosfet follower at x0.8, giving a total of 3.2x which is about 10dB... but hey don't quote me on that


There's no way to simultaneously control volume across two amps in balanced mode, so for the most part I found myself leaving both amps at max and fiddling with volume on my dac (which outputs 2V balanced). This was fine with my HE-6 which just wanted more and more, but with more sensitive headphones I eventually cut up some stickypaper and marked the knobs with arrows so I could roughly set the volumes at the same spot to give myself more play on the dac.


With HE-6: amps maxed, dac at 75%

With HD598: amps at 30%, dac at 50% (if amp maxed, dac around 10% which is too little)


Noise was never heard, even with the amp maxed out with sensitive headphones and the music paused. No pops or other things during turn on/off.


Now since this is a class-A amp, it does run pretty hot. Temperature readings:

- around 50-60°C (140°F) on the surface

- when stacked the bottom one reaches about 60-65°C. Readings inside the vents reach about ten degrees higher. (around 120-170°F)

So it's not hot enough to cook on, but hot enough to be uncomfortable to the touch.




The Sound

Alright, enough with the blither blather. You want to know how this thing sounds. In a word: Impact. In a second word: Muffins. Because muffins are great. I like a lot of gear, but it's not often that I am really enthused about something. My first such experience was with a Bottlehead Crack amp. As the years have gone by, perhaps I've become more jaded or spoiled or harder to impress or all of the above, but fewer and fewer components have really wowed me. Well, the HA-200 have stepped up to bat and I find myself continually surprised at how much they deliver.


Actually upon first listen, I wasn't too impressed; I thought the sound was a bit too “heavy” and in your face. I thought the wrong things were being emphasized, but it turns out I had it backwards and was just used to mush. Once I had given myself some time to adjust to the new sound (you always have to give your ear time to acclimate to new toys), when I later tried to go back to the old rigs it just wasn't gonna happen. In the past when I've moved from rig to rig, things would feel different and I'd have to re-acquaint my ears until I could better qualify my impressions. This time though, moving away from the HA-200 made me acutely aware that I was stepping down the ladder.


Most listening was done with my Hifiman HE-6 (modded), but I also had a Sennheiser HD 800 and HD598, Mr Speakers Mad Dog, AKG K612. Grado HF2, etc. So I've covered a decent range of impedances and sensitivity. Only the first three were used in balanced mode.


There isn't too much that I can say here that doesn't sound like hyperbole or purple prose, so I'll just jump to a couple comparisons. My primary amp for a while was the Nuforce Icon2 speaker amp (see my profile for a review), a diminutive class D amp barely the size of a book. I'd gone through several other amps, but kept coming back to the Icon2 for the size to performance ratio. The Centrance Dacmini PX and Nuforce STA-100 had their turns (again, see my profile for reviews), but I still rotated back to the Icon2 after some time. The PX came close to staying, but it eventually got moved into my bedroom speaker setup. I briefly went through a phase where I tried several vintage stereo amps, but those were just too huge for my desk even if they did provide the necessary grunt. So anyhow as I was saying, I bounced around with a bunch of different options but none I felt offered enough of a jump from my Icon2 to justify the larger size... that is until I got the HA-200. Even with just one in single ended use, it was a pretty good bump in sound quality. With two playing as monos, there's no going back... at least not for the next few months until the fickle mistress of upgrade-itis rears her head again. That isn't a knock on the HA-200, I'm just being honest with myself and my semi obsessive need to rotate through more gear. The fact that I've even had them more than two months is a testament to their staying power.


So looking back over my last paragraph, I didn't actually compare much. Ok how about this...


I have an older Meier Corda Aria amp. It's discontinued and kinda rare and probably no one has heard it, but tonally it's surprisingly kind of similar. Still, no contest.


The Yulong DA8 is a fantastic piece of kit, and actually serving as a dac feeding the monos is possibly my favourite pairing that I've heard so far. In terms of comparing the amp outputs though, the DA8 has a lot of power behind it but doesn't quite have the sheer authority of the monos. I would put the DA8 in the same league as the Wadia 121, and slightly above the Nuforce DAC-100 that I've previously reviewed (though in specific pairings, I would say the DAC-100 edges out the Wadia and Yulong when driving the HD800).


I've also heard the Yulong A18 and A28, the former slightly more expensive but not truly balanced, the latter slightly cheaper and also balanced. Both are good amps in their own right with their own flavours, but I would put them decidedly below the HA-200 monos. With all the Yulong gear, they just didn't quite have the same grip, especially in the low end.


The Lyr? To this day the only headphone I've enjoyed off the Lyr is the LCD2... and I think it sounds better off a Vali anyways.


Someone's probably going to ask about the Mjolnir. I heard one a while ago so I'm going by memory and can't compare directly, but honestly I didn't like it. It felt too heavy and pushy/in-your-face. The HA-200 has the strength and a bit of aggressive edge, but isn't angry with it like I felt the Mojo was.


Oh there's the very popular Emotiva Mini-X. I'd heard a lot of good things, and was even tempted to give it a try despite the little voice in my head telling me to ignore the hype. So a little while ago I saw a used one pop up locally, but I decided to pass on it. Then months later I organized a meet and had a chance to hear the little Emotiva that could... except it couldn't. I'm sure it might be a nice amp for speakers, but as a headphone amp it's really not up to the hype. Lots of power on tap, but it's physically huge (relatively), has way too much gain so you have noise issues and no volume control, and in terms of sonics quite frankly doesn't hold up to good headphone amps. The next table over had a Schiit Asgard 2 and Vali, and I'd pick either of those over the Mini-X.


A Violectric V200 put up a very decent fight, even though it only had single ended outputs. The V200 had good thump and drive and a bit more of a meaty feel to it, while the Nuforce monos dispensed with the meat and kicked me straight in the gut (uh, in a friendly way?). While I prefer the monos for their livelier feel, I could see personal preference taking some over to the V200 who want the warmer tonality. The lack of balanced output, but dual TRS could also be a deciding factor. The V200 also costs nearly $300 more than the pair of monos, which is very significant in this range.


A note on the HD800: In my experience so far, Nuforce gear tends to pair very well with Sennheisers. The HA-200 are no exception. When comparing various amps and plugging in my HE-6, I always felt that the monos were a nice step up but it would take a second to start picking out the differences. Repeating the comparisons with the HD800 however were striking. With the HE-6, I could tell there was an improvement, but it'd take me a minute to qualify that “feeling”. Not so with the HD800 which was immediately apparent. Throw every buzz word you want out there: PRAT, impact, detail, yadda yadda, whichever way you want to put it, the HD800 and HA-200 are a truly wondrous pairing. I know in my previous reviews of the DAC-100 and HAP-100 that I said those were possibly the best amps I had heard for the HD800, but nope those are blown out of the water now. As much as I love my HE-6, if you were to twist my arm and tell me to pick one, I would probably sway to the HD800.


But while we're on the HE-6, yes the monos are enough power for decent listening levels, but those who like to rock out hard are going to want a dac with higher output. The HA-200 is supposedly capable of 8W, but it has a relatively low gain of 3.2x, so I'd recommend a dac with a minimum 2V output, preferably 4V. For the record, mine is 2V and I almost never go above 75%, but at times I find myself wanting just a smidge more. I used to have one that could do 4V and running at full blast was deafening but I listened just long enough to tell that no clipping or distortion was happening (at least none that I could detect at those volumes).




So it's obvious I'm quite happy with the Nuforce HA-200. As a single ended amp it's fantastic. As dual monos, doubly fantastic and totally worth the price. If you can't afford the mono setup, start with one and upgrade later! Of course if you're just jonesing for monos, as of this writing it's the only dual mono headphone amp option I know of for under $1k so it's really your only option unless you start bridging or go DIY. For $350 it's one of the best amps I've heard in that bracket. For $700 as monos I think it's actually ahead of the diminishing returns curve.


It pairs fantastically with the HD800, and has enough juice for the HE-6. The noise floor is also low enough that you can use it with iems.


Obviously if you're running monos then you'll need a preamp or a dac with volume control. Either that or you'll have to mark knobs somehow and control each individually. Your headphones will also require the appropriate terminations, or have an adapter made.

Edited by Armaegis - 6/22/14 at 5:44pm
post #2 of 148
Thread Starter 

a closed box, not exciting

It's a box!


opened the box, how exciting!

I don't know why I caption these


all dressed up

Oh hey it's a bag, which is nicer than a plastic bag I suppose. Nice touch.


there's a joke here about turning over and undressing

I've said it before, but seriously someone in their packing plant has a taping fetish


glamour shot

So there she is...


peek a boo, she's winking!

If she winks, that means she likes you


tasty tasty inputs

RCA for regular use, XLR for monoblock config


naked and on her back

Ventilation is good. I found clearance on the bottom seems to make more of a difference than clearance on top



back left: inputs back mid: voltge selection back right: power inlet mid left: linear power supply mid right: custom toroidal transformer

More than half of this is all power supply


amplifier section I spy an OPA2134 - this is the voltage gain stage

The main amp board. You can see the opamp gain stage in the middle, and mosfets and biasing components on either side, and the entire plate underneath is a heat sink


custom transformer


yadda yadda

Moar Powah


linear supply diode rectifier bridge on the far right large capacitor reserve could be regulators and/or supply transistors connected to the heat snk

Power supply board, a whole bunch of caps, pretty sizeable heatsink there too



input RCA on left, XLR on right

the inputs


voltage selection board and iec inlet

IEC inlet


volume pot

volume pot


TRS jack

TRS output


XLR output and the power LED output stage opamp gain stage (OPA2134) mosfet output LM317 to pull mosfet bias

board with XLR output and power LED


IRF510 mosfet output current buffer LM317 to bias into class A

IRF510 and LM317 mounted onto the big fat heat sink


the other side I'm guessing opamp gain is x4 and mosfet follower is ~0.8, giving total gain of 3.2x which is roughly 10dB as specified

other side


hooked up to a Wadia121 dac, custom made dual XLR3 to XLR4 adapter for my HE-6


Echo Audio - Echo2 usb

hooked up to an Echo2 usb pro audio dac

Edited by Armaegis - 6/22/14 at 2:27pm
post #3 of 148
Thread Starter 

reserved if I need it

post #4 of 148
Thanks for the great review !smily_headphones1.gif
is it more 'spacious' than v200 for example ?
post #5 of 148
Thread Starter 

Yes, though that aspect I may attribute more to balanced vs single ended.

post #6 of 148

Thanks for the review Armaegis. You know you've ruined the Emo mini for me, don't you? Here I am, enjoying my little setup, and then I get a taste of the HA-200's at your meet, when I'm suddenly left wanting. Such is the nature of our hobby, isn't it? In spite of the incoming Virtue amp, I may have to get you to make me an XLR3 to XLR4 adapter in anticipation of my own Nuforce monoblocks.

post #7 of 148
Thread Starter 

Haha, or maybe you should get the Questyle monos and make me lust after bigger gear instead :ph34r:

post #8 of 148
Originally Posted by Armaegis View Post

Yes, though that aspect I may attribute more to balanced vs single ended.

Really?? You think balanced outputs make more of a difference then the bridge to mono?

post #9 of 148
Thread Starter 

Er... maybe it's my 1am brain talking but I'm not sure I understand the question. As far as I can tell the HA-200 is bridged and not "balanced" in the true sense. Granted, almost all balanced headphone amps out there are actually bridged amps, so I'm not splitting hairs here.


I do find the monoblocks more spacious sounding than the V200, but in my (albeit not super extensive) experience, balanced outputs in general sound more spacious than single-ended. The V200 also has a slightly warmer fuzzier tone to it, which to my ears invokes a sense of smaller space (not in a bad way; more cozy).

post #10 of 148
Originally Posted by Armaegis View Post

Er... maybe it's my 1am brain talking but I'm not sure I understand the question. As far as I can tell the HA-200 is bridged and not "balanced" in the true sense. Granted, almost all balanced headphone amps out there are actually bridged amps, so I'm not splitting hairs here.


I do find the monoblocks more spacious sounding than the V200, but in my (albeit not super extensive) experience, balanced outputs in general sound more spacious than single-ended. The V200 also has a slightly warmer fuzzier tone to it, which to my ears invokes a sense of smaller space (not in a bad way; more cozy).

Well the whole bridging/balanced thing gets out of whack sometimes. So might as well add to the confusion:) You can have non balanced bridged amps. Pretty hard to balance an unbridged amp though. So I guess my question would be do you think the balancing or the bridging has more to do with the better sound?

post #11 of 148
Thread Starter 

Oh, for the most part I was treating the words balanced and bridged here as synonymous. The amp outputs have roughly equal impedance to ground (at least within the capabilities of my cheap multimeter), so "good enough" to consider it balanced when bridged together. We could add to the confusion that my dac is balanced but not symmetric :rolleyes:


Anyhow back to the question... as I said I'm basically treating the balancing/bridging here as the same thing. I'd wager there's the cancelling of even order harmonics typical of balanced configs to account for cleaner sound, but I don't have a scope to prove any of that so it's not in the body of my review. The extra headroom I'd say maybe doesn't make as much difference, as it was actually too much power with the HD800. The HE-6 is just a pig though, so it always wants more (but that'll come down to the dac, not the amp in this case).


Ok, 2am, way too tired now.

post #12 of 148
Awesome review. I feel my next solid state amp will be a pair of these once I get a balanced source. Great review!!
post #13 of 148
Thread Starter 

It does feel a bit odd that Nuforce released a balanced headphone amp in their Home series, but doesn't have a balanced source in that line. They have their DAC-9 (and soon to be DAC-10), but those cost considerably more in their reference line.

post #14 of 148

Stunning review... thanks so much for taking the time to research and write that up.


My next amp(s)... hands down.

post #15 of 148

Have you tried LCD-2's with this setup? I am curious as to what you think, I'm in the market to step up from my O2+Odac that I use on my LCD-2 w/ fazors

New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › [Review] Nuforce HA-200 - affordable class-A monoblocks