Ah ha - that brings back memories Hamish - I used to have one of these
Lots of EL34 tubes, heated the house up quite nicely!
I built it by hand from a Velleman kit - lots of silver soldering (700 connections), high voltages, and HUGE toroidal transformers.
Specifications
output power: 2 x 90Wrms music power for loads of 4 or 8 ohm
power bandwidth: 15Hz - 40kHz (-3dB ref. 50W)
frequency range: 8Hz - 80kHz (-3dB ref. 1W)
harmonic distortion: 0.08% (1kHz / 1W) / 0.7% (1kHz / 90W)
signal-to-noise ratio: > 105dB (A-weighted ref. 90W)
channel separation: >75dB (ref. 90W)
input impedance: 34Kohm
input sensitivity: 1Vrms at 95W
damping factor: >10 (100Hz)
weight: 23.46Kg
I had a digital pre-amp, and a pair of Linn Keilidhs - probably sounded terrible!
The valve amp is still in my dad's shed I think - buyer collects as it weighs a bleepin' ton