Sound quality impact - preamp vs power amp?

I believe the whole point is to optimize the synergy among your components & room to best connect you to the music and stir your soul.

Bingo!

A synergistic system that stirs the emotions is the ultimate goal. This can and often does result from very unusual combinations. You cannot simply throw money at the problem either. So when I see someone is using $1K speakers with $10K amplification, and vice versa, I no longer assume he/she is a noob. 

The amp and preamp are both just as important as the other. If I spend 7K on a preamp, then I will spend 7K on an amp and probably by the same manufacturer.  Synergy is everything. 

Assuming the rest of the system makes sense, I'd usually suggest a better preamp, having heard and done way too many demonstrations of how a better preamp is generally preferable to a better power amp.  

Again, assuming the system makes sense in the first place.  

Pre amp maybe assuming amp tip top. Can of worms my final answer. Open the briefcase please.

Lot’s of great separates and lots of great integrated set ups. Everyone typically espouses the gear they have or want.

Maybe the room is great or maybe it’s poor.
If you a thrilled then you have the right synergy for you.