Watts - Volts and Resistance

The note on the back of the receiver probably says that it draws 535 watts of AC power when it is maxed out driving 4 ohm speakers. This would suggest that its total audio output is probably about 50 percent of 535 watts, which is 133 watts. You say that is a 4-channel amp, so 33 watts/channel would be a good guess.
The 8 ohm audio power will be less...I would guess about 20 watts. All of this would be with all channels driven, so the power capability of an individual channel will be more.

The '535' and '675' must be power-CONSUMPTION amounts. The '4 Ohm Max.' must mean that power compumption is while the unit is delivering maximum power into 4-Ohm speakers.

Those numbers have nothing do to with the audio-power output.

Why not connect it to some speakers and hear if it delivers enough clean-sounding output?
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Thanks for the replies.
I hokked up the receiver(I think it was made in 1976), and beleive me that I'm sure it delivers a lot moer than 20 or 30 wpc. I'm driving a pair of 3 way floorstanders that play loud and I can't get past 40 % of the volume, it's just too loud.
It sounds quite nice for an old receiver !!!

Rgds.

As I recall, the Quad receivers from the mid '70's were only good for 20-30 wpc [max] into 8 ohms. Quad was a format disaster, and Quad amps were only produced for 2 or 3 years. You should be able to about double that power into 4 ohms, but bass damping and the amp's stability might be a problem with a 4 ohm load. What are you using for speakers? Do you know their efficiency? Can you bridge the 4 channels into 2 channels?