Features

• 30 V supply voltage
• Dual-rail LDO regulators for a clean power supply
• Power control circuit with low-battery warning, automatic shut-off and an electronic fuse
• Converts the balanced input to a high-power single-ended output

Balanced-to-single-ended conversion has three advantages. Battery life is longer and heat is lower (about 9.5 hours, against about 6 hours for a fully balanced design). Images and positioning become even more distinct. And white noise from the DAP tends to cancel out between the + and − signals (this varies by DAP). Combined with the high 30 V supply, the result is a very powerful sound.

Balanced-to-single-ended vs fully balanced

A true all-genre amplifier: please listen and judge for yourself. It reaches its full potential after 50 hours of burn-in, and 20 minutes after power-on.

Power control

When you switch the power on, the white LED lights. When less than about one hour remains, the white LED blinks to tell you it is time to change the batteries (at under 10% remaining capacity, so this does not cause a memory effect). When the batteries are judged empty, the LED turns red and the amplifier powers off. It recovers when you replace the batteries. An electronic fuse also protects the amplifier circuit from burning out in the unlikely event of a fault.

Gain switch

A switch on the board turns the input attenuator on or off (ON: ×2.56, OFF: ×1.28; shipped ON). If you hear white noise with high-sensitivity earphones, or the volume is too high, try setting all four small switches to OFF together.

Specifications

Input	4.4 mm 5-pole balanced
Output	4.4 mm single-ended
Supply voltage	30 V
Gain	×2.56 (×1.28 with the gain switch OFF)
Max output	1700 mW @33Ω
Frequency response	5 Hz – 4 MHz (−3 dB)
THD	0.0017% (30 kHz LPF)
Output impedance	0.25 Ω
Batteries	6 × AA (NiMH or alkaline). Fujitsu black batteries (HR-3UTHC) recommended
Battery life	Approx. 9.5 hours (black batteries)
Volume control	None (to avoid degrading the sound; adjust the volume on your player)
Operating temperature	0–40 °C (non-condensing)

Precautions

• Turn your player's volume down and connect from the headphone output (phone out) or a variable line output. A fixed line output plays at full volume and can damage your hearing and your earphones or headphones.
• If you take the board out of its case, never put it down on metal. The batteries could burn.
• Using any single-ended adapter other than "SE-Attach" on the output voids the warranty.
• Batteries other than NiMH, NiCd, alkaline or manganese are used at your own risk.