I received this last week to try out along with my Mesa M-9.. It sounds fantastic, very nice warm tubey tone..It's in great shape.. It's a tough call, but I decided to keep the M-9.. This is the newer version with the speak-on connections.. Heres is a link to the original ad..
FS Mesa M-Pulse 600 in minty condition
Asking $800.00 + shipping.. If you want, I can throw in a 4 space rack bag thats in good shape for $50.00 extra..