I haven't opened the SA-XR55 up yet.
It is playing in a bedroom system with the incredible Onix X-LS and X-SUB.
ABSOLUTELY FANTASTIC speakers for $400.00 including the sub!!!
Source is modded SB2.
This little system sounds so good, I am hesitant to take it down to look inside the Panny
I do have a modded SA-XR45 here I need to check out. I will most likely pull the 55 out and put the 45 in to see how they compare. Then I may just open the 55 up. I don't think the 55 or any newer generation Panny receiver will ever have a PS like the 45 again. The trend is smaller and lighter switching PS.