Actually James, they are a really imrpessive sounding amplifier. Very strong, very firm and 'old-school', but prime candidates for a DC-sensing relay disconnect!!!
Whenever one of those TO3 transistors in the "wind-tunnel" goes collector-emitter short, they put out the full, unregulated rail voltage (what is it... 70V or something?) into the poor speaker...
If you could run it through a fast automatic DC-sensing disconnect, then they will indeed make a decent monitor amp though...
Keith