The center tube is rectifier tube. A pair of 6SN7 driver tubes sit on both side. A pair of 6080/6SA7/7236 power tubes place on either side of the amp.
Face panel from left to right: balanced volume control, 3-pin XLR headphone output, 4-pin XLR headphone output, 1/4 (6.3mm) inch headphone output, high/low impedance switch and power switch.
Right side
Multiple-outputs in different terminals that allow 3-pin XLR mono, 4-pin XLR stereo, and 1/4" phone jack
The volume control is a 4-channel balanced stepped attenuator.
Back panel from left to right: AC inlet with fuse box, AC110 and AC220/240V voltage switch, RCA audio input, XLR audio input, RCA and XLR selector.
WA22 hd800 and T1

I have since tried HD 800’s with the prototype Woo Audio WA 22 amp (which is tube rather than solid state apm that has variable output mpedance). The WA 22 takes the sense of vividness up a notch, mostly by making the midrange contrast level higher, while introducing minimal if any deleterioius side effects. The mostly subtractive errors noted above are still there, but they are diminished in the overall presentation. This gets me to the level of really, really liking the HD 800s. The HD 800s are so good that I could easily live with them over the long haul. (AVguide Buyer Guide 2013)

Price: $1995

* Included tubes: 1 pair of 6AS7, 1 pair of 6SN7, and 1 274B

* Tubes shown on the pictures are not included.

* AC power supply cord, interconnection cable are not included

* Shipping charge applied to CONUS only. International shipping charge will be invoiced when your order is in our system.

Owner's Manual(PDF) pdf-icon

    Technical Specifications:
  • Headphones impedance : 8—600 Ohms
  • Input impedance: 100 Kilo-Ohms
  • Frequency response: 8 Hz — 50 kHz, -3dB
  • Output: 1500mw @32 ohms, 700mw @600 ohms
  • Signal/Noise: 92 dB
  • THD: <= 0.3%
  • External dimension: 7”(H), 12”(W), 10.5”(D)
  • Weight: 25 pounds or 11.4 kg
  • Voltage: AC 110/220V, 50/60 Hz
    Standard Features:
  • Point-to-Point wiring
  • True balanced topology
  • All tubes. No semi-conductors in the entire circuitry
  • One 5AR4 [PDF] rectifier tube. Direct substitute: 5U4G
  • Two 6SN7 [PDF] drive tubes
  • Two 6AS7 / 6080 [PDF] power tubes
  • Smooth balanced attenuator
  • One balanced XLR input
  • One single-ended RCA input
  • Two 3-pin balanced headphone output (left and right ch)
  • One 4-pin balanced headphone output
  • One single-ended headphone output
  • High and low impedance switch

Power tubes upgrade:
Tung Sol 7236 NOS 1963
Hand-pick matched pair
$200 (2 pcs)

One of the best power tubes available for this amp. The 7236 vastly improves dynamic and soundstage. It has a very good speed, warm mid range, tight and deep bass. Buy and ship separately.

Driver tubes upgrade:
Hand-pick matched pair
GE/RCA/Sylvania/Tung Sol 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 upgrade 1:
Takatsuki TA-274B single
$1045 (1 pc) with 1-year warranty

Takatsuki 274B offer ultimate performance to any current production 274B's. Users have claimed that it exceeds the quality to NOS Western Electric 274B.

The TA-274B sold in an individual package Click to see details.

Rectifier tubes upgrade 2:
KR 274B High-Resolution, single
$647 (1 pc) with 6-month warranty

The KR Audio 274B HP rectifier tube is a perfect compliment to any tube amplifier’s high voltage power supply. Solidly made and very low in microphonics make this a no brainer to properly power the finest tube amplification. This latest high performance design better controls both electrical and vibrational resonances that blur imaging for greater clarity to the source.

Image of a KR 274B HR rectifier

Rectifier tube upgrade 3:
Sophia Princess Mesh Plate 274B rectifier
$160 (1 pc) with 30-day warranty
Wide open soundstage, full body, silky smooth, a great combination with the above tubes. 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.