NuPrime HPA-9 headphone amp & preamp

General Information

The NuPrime HPA-9 is a pure Class-A headphone amp and preamp with low temporal distortion and lifelike sound. The single-ended Class-A design and non-feedback output stage are capable of handling wide fluctuations and range of headphone impedances from 16 to 1000 ohms.

HPA-9 was derived from NuPrime DAC-10H, which won The Absolute Sound Product Of The Year 2015 award. The headphone amp of DAC-10H was compared to high-end standalone headphone amp costing as much as $3000. Today’s best headphones can cost as much as a high-end DAC. Their owners demand a headphone amp that fully exploits their potential. High resolution DAC chips are starting to be incorporated into smart phones and that would further drive the need for high performance headphone amp that can be used with a wide range of in-ear and over-ear headphones. Phono input is included for vinyl enthusiast.


- Single End JFET input stage circuitry design provides the very good second harmonics. And provide high input impedance and ultra low input bias currents. As well as high S/R.
- Non feedback output stage design provides low Temporal Distortion and natural sound.
- Pure Class A headphone amp design.
- Phono (RIAA) input module: Internal setting to MM or MC.
- Supporting up to 3 headphones simultaneously.
- Maximum headphone impedance support range from 8 ohm and up to 1K ohm. Although many headphones state that the nominal impedance is at 300 Ohms, however, during some frequency (100Hz for instance) the peak impedance is actually at around 700 ~ 800 ohm. The HPA-9 does not have such limitation.
- DC offset protection.


1 x Phono Stage
2x Analog Stereo RCA

1 x 3.5mm earphone out
2 x 6.3mm headphones out
2 x pair of stereo RCA out
THD+N: < -110 dB (1 kHz / maximum gain)
Frequency Response: 0 Hz to 200KHz (-3dB)

Latest reviews


My name is grizzlybeast and I'm an audioholic.
Pros: Nice bass, not harsh or sibilant, Great sound, Excellent Value, versatile functionality, Organic,
Cons: could use a little more airiness(for some headphones), no other cons really.



Knowing that diminishing returns is such a reality it can be a bit heartbreaking to climb up the latter and experience so little change in sound quality. For the most part we want something that brings us the most realistic sound we can get for our money. Even if that reality is something we have shaped by our personal tastes for bright, lean, full, aggressive, or smooth. Even though some qualities can be explained technically, our personal value of each quality will vary. So what does an amplifier need to do to punch well above it’s price and humble the top of the line amps out there that yield great disproportionate results? Well based on diminishing returns, not much. From my previous experience with Nuforce, and now this Nuprime HPA-9 I really believe that NuPrime really understands this concept very well. Maybe a little too well (if there is a such thing).  They continually seek to engineer their products to punch high for their price. 
With bold statements such as “HPA-9 is the ultimate headphone amp capable of competing with any headphone amp at any price.” or them boasting how it measures like a $3000 dollar amp, you would think they are biting off more than they can chew. I only have one TOTL amp at the moment and got to shoot it out vs the Audio Heron H5 to put these claims to test… Feel free to jump to the sound section to read how it faired in my opinion. Just make sure you come back to the headphone pairing sections, functionality etc so you can get the whole picture because despite its stature it offers quite a bit for your buck. 


The Nuprime is capable of being a phono amp; has three headphone outputs that can effectively be used simultaneously without any real loss of Fidelity or power; the ability to plug three sources in at the same time (one being a turn table) and toggle between the sources via the knob on the left and a low, high gain setting to properly provide juice to your headphones. 
The only thing it really is missing is balanced ins and outs. 
Concerning its powering ability and internal design, allow me to simply quote the Nuprime Representative because I am admittedly incapable of explaining this adequately. 
“FET Input Stage: The single-ended JFET (Junction Field Effect Transistor) structure is powered by voltage with the characteristics of a solid-state semiconductor very much like a vacuum tube. The HPA-9 therefore produces a sound very close to a triode's. The high 2nd harmonic also contributes to the sound's warmth and neutrality, with an especially rich midrange.
The amplification circuit: The HITACHI 2SA872 and 2SC1775 transistors are no longer in production. However, we managed to acquire sufficient inventory for HPA-9. We have chosen these transistors because of three important features of a small-signal amplification transistor: high HFE for high current capability to power hard-to-drive headphones, wide bandwidth (FT) and low output capacitance (low COB). The result is a natural, high-resolution, detailed and wide-bandwidth sound.
Non-feedback, pure Class A output stage design: Non-feedback design with very low nonlinear distortion is difficult to accomplish, but when achieved, provides a smooth sonic characteristic. The design's best example is the Swiss darTZeel NHB-108 amp priced at about $20,000USD. The HPA-9 uses a 40W transistor specification for the output stage and an extremely precise KOA 0.1R.13W resistor with ideally quiet current consumption. Such an innovative design makes the HPA-9 a one-of-a-kind headphone amp.
World-class power supply: HPA-9 uses twelve 2200uF capacitors to form a capacitor bank array, and when the auxiliary capacitors are included, provides 30400uF of reserved power capacity. We are not aware of any other headphone amp using such a design, typical rather of high-end power amps. The massive capacitance array provides abundant power to drive any high-impedance headphone. 
To drive high impedance headphones properly by simply increasing headphone-amp power is insufficient. A brute- force, high-power design can cause the headphones to be played too loud, often resulting in long-term hearing loss. By providing large, instantaneous amounts of power through 30400uF capacitor array, a pure, Class A design of a high current and low impedance output stage, the HPA-9 is able to drive high-impedance headphones with ease while providing just the required amount of power for high efficiency earphones.”
The amp is fairly deep, not really wide, but shallow in height measuring 9inches wide, 2 inches tall, and 11 inches deep. My unit arrived in black (different than my request) with silver nuprime labelling and faint grey lettering to identify volume, gain, and input selections. It weighs an solid  and compact 5 lbs which is not really heavy at all for its price. 
The volume knob doesn’t have much resistance but is very easy to dial in your ideal listening level. For the whole time I have had this amp it has worked flawlessly in every way. Something I can’t say about my last amp, the Liquid Carbon but I also can’t say which one overall represents the better value. 
Even though the aesthetics from the sides reveal all of the little bolts, and separate plastic and metal parts that make up the chassis, I kind of like its modern design and isolation feet underneath with the rubber pods that keep it from scratching my white desk.



2015 27 inch iMac 5k retina display
LHLABS Pulse Infinity DAC and headphone Amp.
MHDT Stockholm 2
Audirvana Plus
Amarra SQ
Airist Audio Heron 5 (tour unit)
Trafomatic Head 2
Sennheiser HD800S, Fostex THX00(on loan from member Soundsgoodtome) , ZMF Omni, LCD2.1 (not much time with it though)


I wanted to breifly cover how well the HPA-9 is able to drive every pair of headphones with ease despite its meager Max 450mW @ 32 ohm / 100mW @ 600 ohm rating. This is the first and probably the only headphone amp with a rating that low that can grab my Omni by the balls and make them sing. It is not the best pairing here I will admit but for reasons mentioned above something is definitely going on in the design that makes them hesitant about listing that spec on their website. It will mislead you for sure because this baby has plenty of juice on tap that has more to do with current than your average amp. The NuPrime  provides enough current for me to feel that listening to the Omni with the knob halfway will be fatiguing for long sessions. I  usually like to listen loud for two minutes of my favorite song and then turn the pot down for the rest of a play list to avoid fatigue yet 12 o’clock is pretty loud on high gain. Dear reader, if you were once puzzled by the 12 o’clock etc terms like I was let me help. I look at the volume marking like a real clock . This amp turns on at 7:30, 12:00 is dead center and I don’t know what all the way is and won’t try it!!). I have yet to go past 1:30. One thing is that low gain is almost as loud because for the same volume it is only at 1 o’clock on the pot. However I loose a little bit of dynamics in comparison to high gain with hard to drive headphones as it sounds slightly more compressed. 
At first, at high volumes my experience was that past 12:30 the ZMF Omni began to distort however as more time went by (burn in) I noticed a lot less distortion to the point that now I can play it painfully loud and its all clean…. Later on I will talk about headphone pairings but I had to clear up any and all perceptions that this amp can’t drive almost any headphone, because it can!!! Any other headphone amp rated such would not be able to. 
Lets get to the sound now…



I don’t recall the Nuforce ha-200 sounding like this, nor having this much headroom even though rated more powerful in mW’s. Neither do I recall the Nuforce I-DAC sounding like this either. I may have a faulty memory but I was expecting a bright and sheeny kind of signature with some digital grain reminding me I was listening from my computer. I am not saying that is what the other Nuforce gear sounded like but I do recall some of that going on with the Nuforce I-DAC. The 9 is down right incomparable. 
While I wont call the sound liquid or silky smooth, the amp is a bit different in almost every way than I was expecting. It certainly has it’s own signature that will impart a bit of it’s flavor into your music but the for the most part bleeds and inviting warmth down low and lack of glare and airiness up top. I find it neither forward or laid back but a really good middle ground of aggression. Musically natural is what this amp is.  



The NuPrime at first seemed slightly less tight in the bass than my infinity amp, but that was only in perception because the 9 is actually more solid. It's just that the pulse infinity amp section is a bit dry and pushes a perception of being technical, whereas the Nuprime bass is actually just naturally integrated into the music. Down low there is a slight warmth that doesn’t necessarily sound like a bass boost is on but more like there is a gentle raising of the bass overall. The texture is excellent and the punch is controlled, solid, and weighted. In comparison to the Airist Heron 5 it is head and shoulders above it in slam, punch, control, and presence. Even compared to my Trafomatic HEAD 2 the bass seems more solid for Orthos and lower impedance headphones such as the Fostex TH series. The Trafomatic HEAD 2 has an impedance switch and is a 2500 dollar headphone amp furthermore it is a tube amp. However the bass isn’t as detailed as the T2 and when I use the HD800S the bass becomes more solid on the Trafomatic by just a little. The results seem to be that it is better controlling lower impedances regardless of the volume on the pot but make no mistake, the HD800S still sounds controlled and solid with the HPA-9. Its bass performance is most apparent with the Fostex THX00 and really makes for a satisfying experience…well there is a spoiler for you. 


I find the midrange to be smooth, not thin in texture but not really forward. There is a barely noticeable but larger distance of the vocalist when comparing to the Heron 5, infinity amp section, and especially the Trafomatic Head 2. Yet there is still that warm hue that lends itself well to male vocals but overall there is a tiny bit of airiness missing for me (depending on the headphone/HD800S shows no signs of this) that can help lift the veil of darker headpohnes. This is a little different that I was expecting but I actually would consider it very close to neutral. The Heron 5 sounds a lot more airy and pushes the perception of clarity a little better. Yet, I find the HPA-9 to have better body and sound a tad more refined and wholesome overall. The timbre of the 9 is a slightly tinted but very tangible and pleasant. This sounds pretty even through out the frequency range, yet just pinch darker than the other amps I had here leaving the female vocalist a little un-pampered but true to the recording. The Trafomatic HEAD 2 is not dark or bright, maybe just a little sweet in the midrange and lower treble, yet magically without any glare. In comparison to that amp this one is only a hair darker, almost as full bodied in the middle mids, but not as present in the upper mids as the T2 or airy. For airiness the Heron 5 takes the cake, yet it is not bright either and is relatively smooth but sounds kind of more open with good treble extension. 
For the Nuprime, still I find the mids to have adequate details and good resolution with a warm sound that, while not like a tube amp, is great in realism. If you are looking for that crisp and laser sharp sound, the HPA-9 is probably not the one for you. If you are looking for your midrange to be even like the recording probably intended with no flattery than maybe you will appreciate the Nuprime HPA-9'S tuning like I do. 


Depending on the pairing it can either be great with Macro dynamics or 
decent. Planar magnetic headphones never really fully become as animated like a dynamic driver does and this will not be the amp to make it do so. What I do get with my Omni is a reinforced body, firm and dense / weighty tones that orthos are known for. In comparison I felt the Lhlabs headphone out to sound as if it was faster but a bit more forced and digital sounding.   I do find this amp to be nicely punchy, not super fast, but musical without unnecessary aggression. 
The head stage of this amp is spread out with limited boundaries but it is more developed than the pulse infinity amp section. Both of the other amps here have more spread out sound stages than the HPA but it’s not really a fair fight because the Heron 5 is exceptionally wide for a solid state and the T2 has the most 3 dimensional sound I have heard yet from an amp. I would say the 9 is still above average, especially for its price. It has great separation, even better than the wispy heron 5. One of the things I love about this amp is how all of my instruments sound distinct, separated, imaged, and fleshed out. The Nuprimes ability to sound cohesive is supreme as nothing ever feels disjointed and my music always has a good foundation and tone. Lots of toe tapping here because the good separation along with the dynamic sound makes for an immersive experience. 
The amp is very clean sounding overall and despite me thinking the Heron 5 sounds more airy, I prefer the body and emotion of the 9 as well as the separation and definition of the individual notes in the end. The Heron sounds just as detailed but because it lacks tonal weight the music seems more blended than this.  I also love how the 9 does bass, and is more even tempered than my Trafomatic Head 2. They compliment each other very well. 
This amp seemed to have  a blacker background when using the Infinity as a DAC than the Infinity headphone out. Sometimes the Pulse infinity amp sections accentuations make sound higher in  resolution.  Especially because it is a little brighter, and more aggressive, but it sounded like it was less refined, a little more hashy and raw. While I sometimes preferred the raw sound of that amp…in the end the heavier toned and warm sound of the Nuprime made a better pairing with that DAC. Fast forward to my MHDT Stockholm2 and I have a really musical combination. Also the Stockholm 2 reveals the Nuprime to be a better performer on female vocals than it did with the Infinity DAC albeit equally behind the Airist and Trafomatic 2 in that regards since they all improve in that area with the S2. 


  1. with the HD800S
The bass is pretty tight. Instantly agreeable in tonality and balance. The Dynamics are decent though I would rather have something with a more spacious sound to compliment the HD800S. This could be because leaving the Trafomatic Head 2 socket for the Nuprime never seems like a good idea no matter the song. For adding a little warmth and punchiness to the relatively thin Sennheiser the Nuprime is hardly useless.  High gain is heaps better for the HD800S as the bass firms up substantially and adds tonal weight overall
  1. with the Omni
Again bass seems controlled but probably not optimal for getting the best dynamics and punch from the Omni. A bit too warm in the lower mids at times and doesn’t add any speed to the heavy and rich sound of the Omni. Again it is really surprising how much power it has to get it that loud but it still isn’t an effortless listen with the Nuprime. The thing is though is that neither are any of these amps I had here in comparison. The Heron is too smooth in attack.The trafomatic sounds good but Id like to try a better and faster solid state amp with gobs of power to exploit the Omnis potential because it truly does like tons of power. Halfway up on the pot and the Omni can get above normal listening levels but I am in consistent want for a bit more air like the Heron provides and sometimes I feel like it is held back a tad as the ultimate pairing. Yet and still I choose the Nuprime over both of those amps for listening to Electronic and bass driven music. The Heron again is the easy choice for vocals and openness by a long shot. And at the new price of 999 USD the heron 5 is still within range of being a competitor to the Nuprime. 
  1. with the THX00
YEAH…. this is golden right here. This sounds better than all of the other amps for the THX00 on exciting songs. My infinity is now gone because I felt satisfied with the Nuprime and wanted the MHDT so I can’t really say with certainty that it is better than the infinity amp for the THX00 but Id be very surprised if it wasn’t. Sometimes the THX00 can sound like it needs to be kept in check when songs get busy, and while the nuprime doesn’t totally stop the blending it definitely helps. The bass on the Fostex compared to the Omni is a little uncontrolled but boy does the Nuprime hold its reigns and brings out very nice slam and punchiness. The warmth of the 9 and linear treble balance of its tuning, gently buffer the glare of the THX00 but only slightly as to not hinder its perception of a forward and breathy vocal run. If you are looking for an amp for your THX00 I would say stop right here. 


I really believe the Nuprime offers supreme value and is never the worst pairing for any headphone. Does it punch as high as the Nu entity claims it will in price to performance(besting amps 1k and up)? In some areas yes but in my opinion if it was tuned to be slightly more airy it may have tricked the average listener into thinking they have the best amp out there. However, I am not a fan of boosted highs in gear and that may be a bad thing for already bright headphones. Overall it has a lot going for it and is an easy recommendation for someone looking for an amp that can play with most headphones and then some. My Trafomatic Head 2 has an impedance selector of 25,50,100,300, and 600 yet it seems and sounds less versatile than this amp. Good clarity, refinement, and musical tonality make this headphone amp a real winner in my book. 
~ Grizz

update and addendum 6/17/16
After burn in and more time with this amp I have to make several points. I have recently paired it with my Metrum Pavane, a DAC that costs 4,999 brand new. I am absolutely floored by how this amp changed when being fed a signal from it.

  • the midrange became a lot more forward and clear
    the airiness of the pavane and speed came through marvelously
    and it is now practically flawless sounding to my ears. DAC first is really key
    During the time of this review I was using the Stockholm v.2 and the Geek Pulse infinity. I have also had the opportunity to try it with the Cayin iDAC 6 and heard a slight improvement in sound quality with the Cayin but I had no idea that pairing it with a TOTL Dac would yeild such drastic changes and be able to produce such transparency

Further impressions with the Hifiman HE-5le

  • This amp is very capable of driving the most demanding orthos without skipping a beat. I still don't think it makes something like the Omni slam harder but it definitely has tons of headroom. The HE-5lE is a bright headphone with sibilance problems yet has a very beautiful midrange tonality and transparency. Paired with that headphone I am only at 2 o'clock on the dial and my hearing is very much in danger. Its also very dynamic and snappy with that headphone. Even more snappy than with my TH2. It seems more and more like my TH2 shines on high impedance headphones and this one shines on lower impedance headphones however it doesn't make ortho bass slam harder, yet it does make lower impedance dynamic drivers slam harder in the bass. I compared it to the new WOF Cayin Iha-6 headphone amplifier and noticed that when using that amp it was able to make the ortho bass slam harder but dynamic headphones sounded similar in slam and punch to the Nuprime. The nuprime sounds more meaty overall.
Anyone (including the author) have experience with this amp and Grados?
I can only speculate. but here are my findings... First of all from what I know Grados are forward sounding. This has a midrange that is not so forward but nuetral yet is a punchy sounding amp. As far as control and dynamics it has done wonderful with dynamic drivers that aren't hard to power. The Kennerton Vali, of which is on tour, has an excellent synergy with it as well as did the THx00, JVC DX1000, and others dynamic headphones not hard to power. I am sensitive to treble but would pretty much bet on this being a great pairing since it is not a bright sounding amp. 
Long time ago, but how does this compare to the Schiit Jotunheim, which seems to be in the same price range?


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