Sound quality impact - preamp vs power amp?

In my personal opinion, a preamp works like a music conductor. I have both Aesthetix Eclipse and Atma-sphere MP-1. Both are excellent preamp but have totally different presentation of the music. It's like listening to Bernstein or Karajan in comparison.

The week link in any system will ruin the entire thing.

Yes but be patient, it can only take so much and so at 2 weeks the link breaks.

Take a $50,000.00 system and feed it low quality source and it will sound like a big awful system.

Actually it will sound like a big awful recording. A friend who is really into the Rolling Stones loaned me a whole bunch of their CDs. Until then I always thought Springsteen was the king of great music crap recording but no, its Mick. 

A truly awesome system has the ability to recreate a whole new world. Its not the system's job to sound awesome. Its the system's job to sound like whatever world is on the recording. Whether it be a magnificent concert hall, a magnificent recording studio, or a magnificent 1968 Ford pickup. Don't know why anyone would want that, but there it was. In all its glory. 6x9 coax. Green vinyl dash. With a crack in it. 

Pre-Amp

INMH;  The destruction of the preamp sound is far worse from the transformer of an amp, than is the miniscule interference from the preamp.   A good amp can sound no better than its preamp, but a bigd amp can mask a preamp's deficiencies with enough volume, at least for the general audio public.

Before this year, I would have argued about an amp being first. That was before my intro to Lexicon. I picked up a MC-8 V2.  The Rotel went into deep storage. I’ve never heard a sweeter, more beautiful sounding preamp. And the L7 modes are jaw dropping. I’ve always been a purest two channel guy but with my all JBL surround system (L100t, L1 with twin Harmon 740 subs), it’s absolutely beautiful.