I have been considering hanging an external power amp off my Denon DRA-825R (~1990) mainly because I was under the impression that it may not have enough current drive capability. Yes, I can separate the pre amp from the power amp stage. The back of the receiver indicates that you can connect 4 ohm speakers (the back is stamped 4 - 16 ohm) but with receivers there is always the question of how well or for how long will it drive low impedance speakers.
I finally found my old papers for the DRA-825R and was quite impressed. This receiver incorporates an Optical Class-A Circuit, Parallel-push-pull design, Pure Current Supply (found in their power amps) with Denon's large capacity transformer and ~32,000uF rectifier capacitance.
It is rated:
95W min RMS / channel into 8 ohms, 20 - 20KHz
The DRA-835R is basically the same design and has similar specs. I have the schematics for both and the biggest difference is to the chassis layout which adds more physical separation between the channel circuits and from the power supply.
It is rated:
100W / ch into 8 ohms, 230W / ch into 4 ohms, 330W / ch into 2 ohms
It doesn't specify how long it can sustain these levels before flames.
Given these kinds of numbers, should I still consider an external power amp? Do you think these numbers are over inflated or were Denon receivers just that good?