Well I have had my AV setup for approximately 15 years and looking to do an update. After listening to my friends systems, I feel I want more. I am also going to update my PS2 to a PS3 for GT5, blue ray, and Netflix. My dated system consists of:
Yamaha RXV992 (rated at 80w each channel @ 8 ohm with pre outs)
M&K S100b's L,R,and C (4 ohm and rated 50-200 watts)
M&K S90's L and R rears (4 ohm and rated 50-200 watts)
M&K MX90 powered dual 12" sub (rated 125 rms)
Mitsubishi DD-1000 DVD player
Mitsubishi WD65833 65 DLP Diamond (1 year old)
Direct TV HD
Well I never realized that my speakers were 4 ohm and even though it has worked flawlessly for the past 15 years, I am wondering of I am not using this system to it's fullest potential. I was considering purchasing an amp to compliment my old system. I was thinking of Emotiva amps and these were my options.
1. XPA3 300 watts to the fronts and use the yamaha to power the rears? $529
2. XPA5 $799 300 watts to all 5 channels but out of stock
3. UPA5 $429 185 watts to all 5 channels
I don't plan on going 7.1 and wonder if an amp is even worth it? I am open to any suggestions and I am prepared to get flamed. I have been out of the game for a while which you can tell from my set up.

Thanks for any responses/info and look forward being part of Audioholics.