For the past three weeks I've had a Rotel RMB-1095 amp (200 watts x 5) in my system using my receiver as a pre-amp/processor. I can't tell much difference between that and just my receiver. I think I can hear some difference but I really have to listen.
I had a similar experience. I compared a receiver by itself, versus using the same receiver as a pre/pro, mated to a powerful external amp. I heard some improvement I'll admit, but it wasn't alot. I kept the amp. Much later when finally, I replaced the receiver with a REAL pre/pro, which in my case was an Outlaw 950, my system sounded SIGNIFICANTLY clearly much better. Going from my receiver (in my case it was a Sony) mated to a 200Wx5 amp, to a real pre/pro mated to the same amp, was THE big step.
If I had more inefficient speakers, mating a powerful external amp to the receiver would make more difference. But my speakers don't require lots of power. They're efficient.
[This message has been edited by Will (edited July 17, 2002).]