Why does this circa '75 receiver sound so good?

I am in the process of rebuilding my system and have been listening to a Kenwood KR3200 receiver while I save up the funds for new ARC gear. The more I listen, the less I want to buy expensive gear. This old receiver sounds VERY good with my new Nautilus 805's. I can't figure it out--why? I have also powered the speakers with an Audio Refinement Complete, but the receiver is much more enjoyable--the Complete just didn't sound as good-period. Too much like electronics and not so much like music. I did power the speakers for one night with an ARC D300/LS3 combo and loved it. Don't know what made me think I need something "better", but I already sold the amp, so there is no turing back. Anybody have personal experience with an Adcom GFA5802/GFP750 setup? That has been another consideration lately.