Virtue Audios second-generation Model One.2 Tripath amplifier with upgraded 30V power supply. PDF manual included on a flash drive. Its tiny and unbeatable as a desktop amp, but I routinely ran it to 90dB in a 25x12 room with reasonably sensitive speakers. There was a craze over these Tripath class D amplifier modules starting 20 years ago: the highs taper slightly to deliver a very smooth sound people often compared with tubes. Virtue used a more powerful Tripath module than the competition to create this more serious piece of gear, and made all the capacitors easily changeable for those who like to tinker. You can search for John Darkos review of this model. Features...- 40wpc into 8 Ohms- impedance range 2-20 ohms (e.g., 4 ohm speakers are fine) - subwoofer output (see below)- cool propeller speaker posts accept banana plugs, spades, or bare wire- Stepped volume attenuator- Tripath 2050 amplifier module- Two internal jumpers (slide back the case to access them):* 80Hz subwoofer crossover enable/disable* gain control bypass (i.e., run as power amp and instead control volume from the source). Currently, this unit is configured with the 80 Hz subwoofer crossover enabled and volume knob disabled. Message me if you want me to change the jumpers before shipping. If you run a line-level component through it while its in power amp mode, youll probably blow your speakers. As per the manufacturers instructions, the huge/heavy/audio candy volume knob will be bubble-wrapped separately to avoid bending the volume pot. Just pop it on, ideally with a dab of glue (I never bothered with glue) Measures approx. 5 1/4 tall x 6 deep (including protrusions) x 2 3/4 wide