Axiom Home Page Forums General Discussion Stereo Adding a pre-amp to an AVR

I've been enjoying Axioms (M22, VP150, M2 & 25-31 PC+) for over a year now, basically 50:50 HT & music. I'm now considering "scaling into" tubes for music. A friend suggested I get tube pre-amp and tap the amp section of my Marantz SR-7300 as the most cost effective route. The set-up essentially entails hooking the CD player outs into the pre-amp's line-in and the pre-amp line-out into the CD input of the Marantz. I tried this with a borrowed tube pre-amp and noticed the sound subtly openned up. Any comments on this set-up?