The HPA-300B is a world-class, reference level, headphone amplifier and integrated amplifier. It offers superbly realistic, holographic sound-staging combined with incredible resolution, clarity, microdynamics, and drive. Instrument and vocal tones and timbres are breathtakingly lifelike, and the placement of instruments and bodies in three dimensions is startling, life-size, and addictive. The HPA-300B is silent, except for the music emanating from the blackest of backgrounds. In addition, the stunningly realistic sonic quality is matched by the simple elegance, flexibility, and ergonomic functionality of the HPA-300B’s casework and connection options. The HPA-300B is truly a first-class example of sophisticated, purist vacuum tube audio technology.
 
The HPA-300B is Allnic Audio’s first, and only, combined stereo headphone amplifier and integrated
amplifier. It is based on the glorious 300B triode.  Tube rectification combined with the coveted 61-step Constant Impedance Attenuator makes this amplifier my personal favorite.

The HPA-300B has a voltage gain of +28dB, and a maximum output of 8 watts. It works best with
headphones having an impedance from 15 to 600 ohms and with speakers havng a nominal impedanceof 4 or 8 ohms and a sensitivity of 90dB or greater.

The HPA-300B has the following features:

• All new damper sockets for the tubes in the signal path. Allnic has employed 9 pin tube damper
sockets for decades, but in consideration of the importance of very low microphonic noise for
headphone amplifiers, Allnic developed a new US 4 pin 300B damper socket. In the HPA-300B, all
tubes in the signal path float on liquid rubber, greatly reducing chassis induced microphonic noise.

• New special tube dampers. The 300B tubes in the HPA-300B are equipped with specially designed tube dampers that both stabilize the 300B tubes in their damper sockets and further reduce the 300B tubes’ susceptibility to microphonic noise

• Specialized output transformers. For faster headphone response, Allnic developed a smaller
output transformer than it uses for its standard integrated amplifiers. It provides faster response
time and a wider frequency range and contributes to the HPA-300B’s beautiful 10KHz square wave
reproduction.
 
• Choke transformer drive. For superior driving of the 300B output tubes, Allnic uses the choke
transformer drive method in the HPA-300B. The choke transformer exhibits the best qualities of
both CR and interstage transformer coupling, contributing further to the HPA-300B’s accurate
reproduction of a 10KHz square wave.

• NOS tube rectification. Vacuum tube audio purists generally prefer tube rectification to solid
state. The HPA-300B uses an NOS 5U4G or 5U4GB tube rectifier. The user can try 5U4G/5U4GB
tubes manufactured by different companies and of various vintages to tailor the sound of the
HPA-300B. GZ34/5AR4 rectifiers and their exact equivalents will also work. Others are too weak
and not recommended.

• 61-step Constant Impedance, single-silver contact, bridged “T” type Attenuator. The HPA-300B’s
attenuator, the same as used in Allnic’s top models, has fixed impedance and no (± 0db) channel
imbalance at any volume level. These qualities make a big difference. With a typical
potentiometer-type volume control, music played at low levels can be reduced in scale and sound
quality. With Allnic’s C.I.A, music played at low volume levels remains full scale and lifelike.

• Speaker outputs. The HPA-300B has high quality speaker outputs (for banana connectors only)
that allow it to be used as an excellent, high speed 300B integrated amplifier. Allnic recommends
pairing the HPA-300B with very good, high efficiency loudspeakers. The speakers can be muted
from the remote control.

• High-quality, new and NOS tubes.
• Pure Class A operation.