Ron, I tried that combination after reading your post and indeed it is very, very nice. It does however create a lot of noise (high pitch whining etc...) It dissapears when I change out the BUF634 from ground for something else (OPA627AP). Why would that be? I have since gone back to my favourite chipset OPA111AM L/R > HiC Buf634's > OPA627 top G Socket and bypassed bottom G Socket. This combination seems to suit me the most but am concerned about the thud when turning the P4 on. Will this harm my IEM's?