My now-departed uncle used to talk about how, back in the late '50s, he would show off how efficient his 820 was by hooking it up to a cheapo transistor radio. When I asked him how it sounded, he said "like a *big* cheapo transistor radio".

I had the 820s hooked up to a MC2100 (105 w/ch), which I had plugged into a Kill-A-Watt meter. According to the Kill-A-Watt meter, the MC2100 draws about 40 watts at idle, and about 40 watts at 'loud'. So it barely knew the Altecs were hooked up.