Hi guys, it's my first post in this forums & it's a question to u audio guru's: I have a surround system consists of: KenWood KRF-5030D 110Wx5 Dolbydigital receiver Wharfedale Diamond 8.4 as main speakers(150W @ 6ohm) Pioneer SD-55 as surround speakers (3 way,180W@6ohm) RCA center speaker & a large floor standing 3way Akai speaker(i have it & i don't use it so i put it as a center coz my RCA center is too small) RCA 100W powered Sub anyway i want to upgrade my Receiver & my only options where i live (Egypt) & which can match my budget are those: Yamaha RX-V540 (or maybe RX-V640 if comes down in price) HarmanKordon AVR-2550 Marantz SR5000 there's onkyos & other's but more more expensive. anyway am leaning toword the Yamahas but i have 3 things am worried about: 1-the RX-V540 "not the RDS" is rated as 100Wx6,could it be less powered than my 110Wx5 KenWood espicially that the KenWood can't drive the Diamond8.4's very good i think they need more power???or the Yamaha gonna be more powerful than the Kenwood?? 2-i hear everywhere that the Yamaha is bad in stereo mode??what does that mean & how bad is it??& is it gonna be worse than my kenwood in stereo??? 3-is this yamaha amp gonna be good with my speakers???or it needs better speakers or the speakers needs better amp?? thanx guys in advance & anyhelp will be appreciated.