Which one defines sound: Pre amp or Power amp?


I'm just wondering which component would influence the sound that comes out of the speakers more?

I have a Rotel 5chx120w 8 ohm power amp, Yamaha rxv1800 receiver and Energy RC-70 speakers for HT. I'm trying to make use of what I have and want to dable in a 2-channel setup.
Here are my options:

a) Buy a Mcintosh mc 252 power amp and use my receiver as the pre-amp.
b) Buy a Mcintosh c2200 pre amp and use my current amp(Rotel).

Which one would yield me a better overall sound?
veltraz81
If your system sounds unnatural, change the preamp. If it sounds weak or thin, change the power amp. To dabble in 2-channel, get a separate preamp. You already have a separate power amp. Take care it is safe to operate your 5-channel in 2-channel mode.
Speakers aside how would the mcintosh c220 pre amp fair with a non mcintosh amp? like a bryston or parasound halo
If i was to get speakers I want a 3-way type. How would these mc's pair with gallo 3.1?
I am considering using the C220 to direct my Classe Cam-350s,Rel Stentor and Thiel CS6s.I was thinking of using the Balanced connections for this while still allowing my Classe SSP-300 to drive my surround system unbalanced......