NuPrime HPA-9 Dedicated Class A Headphone Amp w/ phono stage, Black Finish

The best single ended headphone amp on the market?  NuPrime's chief designer, Jason Lim, believes possibly so.  But of course he does, right?  Truth is, at a $649 list, NuPrime's HPA-9 is amazingly good, and not just "for the money". 

If your headphone listening requirements do not include balanced
connections, NuPrime's HPA-9 could be one of the best value choices in
the hi-end  audio market, and deserves serious consideration.  Read on.....

Superb versatility, and pure-analogue design, in a brilliantly conceived high-performance standalone headphone amp / preamp / MM / HOMC phono stage.  HPA-9 boasts 3 pairs of analog inputs, 2 for line level connections m,and one for phono. 

The HPA-9 also allows for direct connection of your turntable

Brand new, open box unit, with full manufacturer's warranty. 

See a well written and very comprehensive consumer review of this amp on Head-Fi.org  here

And click here for an excellent review on Totally Wired.

The NuPrime HPA-9 is a pure Class-A
headphone amp / preamp / MM / HOMC phono stage 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.  3 headphone inputs. 

HPA-9 was derived from NuPrime's award winning DAC-10H, winner of The Absolute
Sound's 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. 

Features:

• 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.


• 30400uF capacitor array for reserved power to drive any high impedance headphone.

 Specifications:

Inputs:

• 1 x Phono Stage


• 2x Analog Stereo RCA

Outputs:

• 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)


• Dimensions: (W x H x D): 235 mm x 55 mm x 281 mm


• Weight: 5.5 pounds ( 2.5kg )


• Worldwide AC voltage: (90VAC~130VAC // 210VAC~ 250VAC) With Voltage Select Switch


• AC Fuse: Slow-blow, T1A, 250VAC
  
  

Innovative Designs

The following design features allow HPA-9 to outperform majority of the headphone amps on the market costing many times more. 

JFET 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 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.

Bring Offers, must sell.