[knowhatimean]

Welll 2W into a 50 ohm load max works fine given the fact the gain structure can be lowered with something all full sized headphone amps should have , a gain setting switch. (Though it was still pretty useless on the 4W max Burson Soloist ; which still had way more than enough on low for the HE-6)

I should have remembered this as I specifically asked about this visible switch on another forum. I wasn't sure if this was for gain or impedance setting !

 

[Kornasteniker]

Already have the HPA-9 here. Really nice AMP!
 
Drives the LCD-2.2 as well as the AKG K702 very well with a good portion volume lvl at around 10-11 o'clock. LOW GAIN!
So it should be quite enough power even for the highest impedance dynamic headphones as the 600 Ohm Beyers or the like. Haven't got a HE-6 to test, neither do I own a K1000, sorry.
 
The soundstage isn't huge but not small either. The NuPrime is quite forward sounding, without the harshness of the Benchmark DAC1. But hasn't got a laid back treble either.
Detail and Clarity are there. Mids are nice woven into the rest of the frequency spectrum, maybe a bit less present than on the Benchmark DAC1. Bass response is relatively flat and well controlled, maybe a bit more punch than a Meier Audio Corda Classic, but that's not difficult. Reminding me a bit of a mixture of the Violectric V100 and V200. So more Bass than the V100 but less than the V200.
 
For me, the NuPrime is one hell of an amp in this price region. Pleasant and forward sounding, without neglecting the locatability of the instruments or overaccentuating the mid frequencies.
The best thing for vinyl lovers: It has a built in MM/MC phono stage! Haven't tested it yet but will do in the next couple of days.
 
Hope I could help you a bit with my evaluation of the amp. OFC all my humble optinion.
 
Greetings, KoRnasteniker
 
Edit:  After listening to the NuPrime a bit longer and comparing it with other amps, i can't help detecting a bit of warmth in the sound signature of the AMP. Probably a good sign to be a nice match with the HD800, though It should complement the tad brighter and less bassy sound of the Sennheiser.

 

[grizzlybeast]

  Already have the HPA-9 here. Really nice AMP!
 
Drives the LCD-2.2 as well as the AKG K702 very well with a good portion volume lvl at around 10-11 o'clock. LOW GAIN!
So it should be quite enough power even for the highest impedance dynamic headphones as the 600 Ohm Beyers or the like. Haven't got a HE-6 to test, neither do I own a K1000, sorry.
 
The soundstage isn't huge but not small either. The NuPrime is quite forward sounding, without the harshness of the Benchmark DAC1. But hasn't got a laid back treble either.
Detail and Clarity are there. Mids are nice woven into the rest of the frequency spectrum, maybe a bit less present than on the Benchmark DAC1. Bass response is relatively flat and well controlled, maybe a bit more punch than a Meier Audio Corda Classic, but that's not difficult. Reminding me a bit of a mixture of the Violectric V100 and V200. So more Bass than the V100 but less than the V200.
 
For me, the NuPrime is one hell of an amp in this price region. Pleasant and forward sounding, without neglecting the locatability of the instruments or overaccentuating the mid frequencies.
The best thing for vinyl lovers: It has a built in MM/MC phono stage! Haven't tested it yet but will do in the next couple of days.
 
Hope I could help you a bit with my evaluation of the amp. OFC all my humble optinion.
 
Greetings, KoRnasteniker

Nice!!! Mine will be in monday. 
That sounds like Nuforce sound signature. 

 

[jasonl]

  ^Please see the above post. It is supposed to be half the power of the dac 10H wich means it is pretty darn powerful for an SE amp. 
THe spects are wrong says Jason. 
So it should be  2 W maximum into 50 ohms. should be we will see the final results soon I am sure. Also that could be the low gain setting for which you are in luck anyway. 

I checked with engineering and the spec is correct but there is a lot of technical reason that it can drive high impedance headphones. I will post the design details here tomorrow. It is going through technical editing now. There are a lot of cool designs that we initially do not want to disclose.
Here's one of the design feature:
The amplification circuit: The HITACHI 2SA872 & 2SC1775 transistors are out of production but we managed to acquire sufficient stocks reserved for HPA-9. We have chosen these special transistors because they have three important features of a small signal amplification transistor: high HFE for high current capability to power very hard to drive headphones, wide bandwith (FT) and low output capacitance (low COB). This resulted in a natural, high resolution, detailed and wide bandwidth sound quality.
Another design feature is the use of 30400uF capacitor array to provide instantaneous power.
 
A lot of high power headphone amps can not be used with high efficient earphones since they use brute force method. Or like DAC-10H, it has to use sophisticated two level of gain stage design which is costly. For HPA-9, we want a relatively low cost amp but world class so we came up with some innovative designs borrowing ideas from very expensive amps such as the Swiss brand darTZeel NHB-108. To drive high impedance headphones well, simply increasing the headphone amp power is insufficient. A brute force high power amp design can cause the headphones to be played too loud and resulted in long term hearing loss. By providing large instantaneous power through 30400uF capacitor array, pure Class A design of high current and low impedance output stage, HPA-9 is able to drive high impedance headphones with ease and yet provide just the required power for high efficiency earphones.
 
more later.

 

[jasonl]

Here's the full text that was added to the product description today:
 
The following design features allow HPA-9 to outperform majority of the headphone amps on the market costing many times more. 
 
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 2^nd 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 bandwith (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. 
 
Summary
 
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.

 

[Kornasteniker]

@grizzlybeast: Have you already got your HPA-9? Would be nice, if you could post your opinion on this amp. 
 
Greetings, KoRnasteniker

 

[grizzlybeast]

It should be here Thursday.

 

[jasonl]

Feedback from a customer in Norway:
Tested a HPA-9 as RIAA with Pro-Ject Turntable/Ortofon 2M Blue pick-up plugged in to a IDA-16 with AudioVector SR3 Avant Garde speakers today. WOW, it outperformed Pro-Ject, s top RIAA Phono Box RS by a mile!
It was tested at the Norwegian distributor of NuPrime who also has imported Pro-Ject for 15 years.
Switched between both RIAA,s many times and was really blown away everytime, HPA-9 had a open and lively sound with "PRAT" as NAIM call it.
Pro-Ject sounded flat and boring in direct comparison. They gonna sell HPA-9 as a RIAA with a bonus.
 
It was posted here: http://www.audiocircle.com/index.php?topic=141053.0

 

[grizzlybeast]

Wow and that is as a phono amp. It's secondary function.

Got my amp today. I ordered silver but got black. Its okay though, O wanted to change it to black any way since most of my gear is black. I will post initial impressions soon with the Omni as the headphone. I was planning on comparing it to the liquid carbon but sold it to get the HD800 S...will be here tomorrow.I'm also on the Airist Heron 5 tour so eventually I'll compare it to that.

 

[grizzlybeast]

 
I erased impressions because I really need to take more time with it so I do not mislead. 

 

[grizzlybeast]

One thing I noticed is that the Omni seems to have almost as much headroom on the low gain settting as it does on the high gain setting. My Omnis get pretty loud on low gain as well. Def not the case with most other amps including the liquid carbon. On low gain I am at 12:00 on the dial and it is really loud. On High gain I am at 11:30. 

 

[jasonl]

The design of HPA-9 has some similarity to tube amp, where it can pump a lot of current, therefore a 10W tube amp can drive speakers. The huge array of capacitors bank (as large as the $3800 Reference 20 power amp) provide a lot of reserve power. If anyone revisit what I posted earlier, we went into design details to explain.
The phono amp wasn't a secondary feature either, it is very good. 
Our engineer is making claim that HPA-9 can support headphone impedance ranging from 8 to 1000 ohm. That's why he is refusing to provide output impedance data as it can be misleading (he did mention that it is quite low).
 
Anyway, the real test is with your headphones and what you hear. Thanks for the feedback.

 

[grizzlybeast]

Still burning in and impressions are becoming more consistent.
The amp has plenty of power. It reminds me of amps that are rated more and everything Jason mentions is true in that regards.

Since my current reference is the infinity balanced headphone out I will describe that amp breifly.

I like it a lot so far but will keep on listening... This is all without being fully burned in. The bass is pretty controlled though and when I say slightly it was after listening reallllllly hard. time can change things. I really thought it would be brighter but it is not dark or bright.... very nice and neutral without being sterile.

 

[grizzlybeast]

Fast forward a little with more time and burn in. This amp with the HD800S sounds more controlled and is better at portraying nuance, microdynamics, and tonal body than my infinity hp out. There is less digital fizzies, no glare, and an overall pure tone to the amp. The only reason my pulse seems more clear is because it's more forward in the presence region and treble. This actually has a blacker background by a little. And actually on the song I tested last night the bass seemed better defined and slightly tighter this time.

What is consistent is that it has a more mellow and warm midrange that is never shouty or forthright. And the Soundstage is better than my pulse for sure.

 

[jasonl]

FFT plot to show the sonic characteristic of HPA-8.  The distinct even order harmonics were part of the design.