Mal, I personally do not like the match-up of Mac gear and SF, particularly with the GH's or Extrema's. The only possible exception to that is the Mac 275 which, while not IMO a great match to the GH's,is the best of the Mac gear I have heard with these speakers. With the Extrema's the 275's are, again IMHO, not powerful enough to really drive them and so I have no Mac suggestions for those.