Newbie Question

Look on the back and see if it has "main out". You should be able to send the preamp section into your desired power amp, if it has these outputs..... but I suppose Marantz would have the definitive answer...unfortunately.

Find an amp you can audition hook it up to "main out" and see what happens with the receiver. Make sure to check that the receiver's five other channels can be used in this configuration. My old Pioneer could, my new Onkyo NR-905 can't.

I looked at the owner's manual for your receiver. You should have no problem running external amps.(page 22)I think you were given bad info.
Jeff

What I meant but didn't elaborate enough to clarify was with the 905 I don't think I can externally amplify the front three channels and use the 905's amp for the four surround speakers (page 47 in the manual) " connect all speakers "
.I'll try again to be certain.

You can. Jeff is correct-it is page 22 in your manual. Use RCA Interconnects from the preamp outs in the lower left of the rear of the receiver to the applicable RCA inputs of the separate amplifier. You won't lose any of the surround modes. I would think, though, that if the Marantz outputs 90 watts while running all channels (some surround sound receivers power the max output into two or three speakers and than it is reduced as it powers more) and if you really need power, going with 125 watts may not be worth the cost of the amp and cables. I have a Pioneer Elite receiver @ 130 watts per channel and have an extra three channel 150 watt amp and not hooking it up as I just don't feel the extra 20 watts is worth the work and interconnectss. (I am eyeing a Mcintosh, though). Maybe you should look at a 200 watt 3 channel amp.