300B Headphone and Speaker amplifier
Amplifier unit on the left, power supply unit on the right
WA5 Headphone and Speaker amp.
Amplifier unit front panel
WA5 Headphone and Speaker amp.
Top view
Close up front
Rear panel and right side
Rear panel and right side
Rear panel and right side

I am completely blown away by the naturalness of the music, the realness of the sound. I listen to a lot of classical and jazz, especially small classical ensembles, piano, violin, cello, that type of music, and it is simply put, a fantastic sound coming from the W5. My K1000 have never sounded this smooth and enjoyable, with NO ear fatigue, no etched treble, and plenty of good clean bass. Not only do the K1000 sound great, but so do speakers on the W5! - by stax-i-nox at head-fi.org

What I can say is the 274B has a very different character from the GZ34 metal base. It is far from subtle. First there is more bass - both in terms of quantity and depth. Second, the overall sound is richer, or I should say, denser across spectrum. Some people may call it "sweet" but not syrupy. Third, the far end treble is not as detailed as the GZ34 and tends to roll off earlier. Overall, it is a very different presentation from the Metal Base GZ34. - fkclo at head-fi.org

Price: $3500

* AMP and PSU ship in a molded foam within a double-wall box

* Power supply umbilical cord is included.

* 1 pair of 300B, 6SN7, and 2 tube rectifiers are included.

* AC Power cord and RCA interconnect cables are not included.

* Shopping cart applies to the U.S. buyers only. International buyers please contact for shipping cost and payment instruction.

Owner's Manual(PDF) pdf-icon

    Technical Specifications:
  • Two 300B [PDF] power tubes
  • Two 6SN7 [PDF] drive tubes
  • Two 5U4G [PDF] rectifier tubes
  • Voltage: AC 110/220V, 50/60 Hz
  • External dimension (each): 8½(H), 9"(W), 17"(D)
  • Weight: Amp Unit: 35 lbs, Power Supply Unit: 40 lbs
    Headphone Amplifier Specifications:
  • Headphones impedance : 8-800 Ohms
  • Frequency response: 10 Hz—60 KHz, -2dB
  • Power output >= 1.5 watt
  • Signal/Noise: >= 95 dB
  • THD: <= 0.08%, 1Khz
    Speaker Amplifier Specifications:
  • Power output: <= 10W x 2, THD <= 3%, 1Khz
  • Frequency response: 16—38 Khz, -2dB
  • Output impedance: 8 ohms
  • Signal/Noise: >= 90 dB
    Standard Features:
  • Independent headphone and speaker circuits
  • High-end output transformer design
  • Point-to-Point wiring
  • Selectable speaker, AKG-K1000, high and low impedance dynamic headphones output switch
  • One 1/4" headphone jack and one XLR connector for K1000
  • Four pairs of gold-plate RCA inputs
  • Selectable inputs switch
  • Two pairs of gold-plate speaker terminals

Parts upgrade: $1210
Premimum parts upgrade package.

(Parts upgrade are intended for amplifier purchase, not to be sold on a standalone basis.)

We carefully selected the best possible audiophile graded parts that bring the ultimate performance from the amplifier.

  • V-Cap input coupling caps. Matched pair 0.15uf/600V
  • Blackgate bypass (6SN7 cathode) caps, 150uf/350V
  • Jensen decoupling caps, 100u/500V
  • Jensen voltage filtering caps, 220uf/450V

Power tubes upgrade 1:
Sophia Royal Princess 300B matched pair
All tubes are tested by us in an actual amplifier to meet the highest quality.
$1200 with 12-month warranty

Sophia Electric applied all expertise learned from the past to this new flagship Royal Princess 300B model. It has the best virtues of both Princess mesh plate and Princess carbon plate 300B tubes and sound light-years ahead of any 300B tubes made in the history including both Sophia Electric Princess Carbon Plate 300B and Princess Mesh plate 300B tubes that won worldwide praises.

The Royal 300B's come in an exquisite wooden box. Click to see details.

Power tubes upgrade 2:
Sophia Princess 300B Mesh Plate black base matched pair.
Comparable to Western Electric 300B. Buy and ship independently.

The result is a 300B mesh plate tube with super clarity, low distortion and out of this world mid range fullness and liquidity. High frequency extension and sweetness is the first thing you would hear. This is a true 300B tube that is 100% interchangeable with the popular Sophia Electric globe shaped 300B mesh plate tubes and Western Electric 300B tubes, as well as current production Chinese/Russian 300B tubes (with WE 300B standard).

Driver tubes upgrade:
Hand-pick matched pair
GE 6SN7GT NOS tubes
We tested these tubes in an actual amplifier to ensure the highest quality.
$330 (2 pcs) with 30-day warranty.

You get a clean and dense sound image with these tubes. It is very low noise, smooth and delicate in the upper frequency range, deep and solid bass, high clarity.

Rectifier tubes replacement:
Sophia Princess Mesh Plate 274B rectifier.
$320 (2 pcs) with 30-day warranty
To impact WA5's sound quality or for your super backup. Buy and ship independently.

Sophia Electric™ 274B tube is a premium rectifier tube for a 5U4/5R4/5AR4 direct replacement with 3X longer plate structure, thus it has a deeper, wider sound stage and even smoothier sound than Mullard 5AR4.