in 2 parts... I have an opprotunity to buy a SWR(tube pre-amp) then I would sell My Ampeg. So heres my questions: #1)How is it that my Ampeg is 500W@2 ohms and 300@4 and the SWR is 450@2 and 350@4? Im a scientist as my day job and I swear the "amp math" gets me all the time. #2)Is it an upgrade to go from the Ampeg B5R to the SWR? Thanks guys!