This is an SPLX 2 channel amplifier, claimed rating of 1200w total; Nick measured the actual power to be approximately 100w rms per channel before clipping. The amplifier consists of a step-up inverter section that provides power supply rails of approximately +/-45v; these are connected to a socket at the far end of the amplifier via high power rating 100Ohm resistors, to provide a dual rail supply for the mixing desk. Ideally this should be regulated down to +/-20v internally; at the moment the resistors drop sufficient voltage to allow the mixer's regulators to handle the input; inelegant, but it works.
The screw terminals for connection have been removed, and replaced by connectors: a 4-pin XLR fixed plug for the power input, and 1/4" jack sockets for the speaker outputs: left, mono, and right. The mono socket automatically bridges between the two outputs to feed mono loads at a higher power. The orginal blade fuses are visible in the centre (second picture).
In heavy use this amplifier gets quite hot; whilst it is (in theory) designed for this kind of use, a future improvement would be extra heatsinks, ideally with fans forcing air through/past them.
(we also have a spare amplifier, actually a four channel unit wired into two bridged pairs. This is a spare for the main amplifier, and can also be used to drive the monitor speakers where necessary.)