It's dual mono, as you can see by the 2 IEC jacks, and weighs 65 lbs. The 4 large toggle switches on the rear top are for setting either full pentode mode, 2/3 pentode-1/3 triode, 1/3 pentode-2/3 triode, or full triode. With 5881/EL34 tubes it gives 150, 120, 85, or 60 WPC respectively. With KT-88-types, it gives 225 WPC in full pentode, and so on down. The black knob over the input jacks is for setting negative feedback level, from Zero dB to Stage I, II, or III (+8 dB). A total of 32 different combinations of mode, negative feedback, and 8 or 4 ohm output taps, (and that doesn't count rolling tubes!). To me, it sounds best on my current Nautilus 803's connected to 8 ohm, in either of the split pentode-triode modes, and either Zero or Stage I (+2 dB) depending on the kind of music or the recording.
The 2 small toggles are for "Isolated" or "Coupled" ground. 4 Bias/Balance trim pots are between the input tubes and transformers. Speaker taps for 8 or 4 ohm, RCA or balanced Inputs.
The meters allow for monitoring output (0-300w/dB scale), and for setting tube bias/balance.
It's driven any speaker I've thrown at it with no problem: Maggie Tympani IV-D and 2.6R, Quad 11L and 21L, Nautilus 805, 804, and 803, JBL 4412 and SR4725X, Martin-Logan CLS-IIa, KEF C-80, a/d/s L990, Apogee Stage, and others. The nice thing is, this amp can be almost any amp you want it to be from the various settings.
I'm also a drummer, and I've even plugged it into guitar and bass cabs when my band was in a pinch. Sounded great! :guitar: