I've been diggin my new (old) Ampeg Reverb-o-Rocket II since I got it about 8 or 9 months ago. I had one of about the same vintage back in the lates 70s/early 80s that I loved but eventually sold of with a bunch of other gear before going to grad school. I'd been itching for that sound again for the last year or two and eventually found one that was near "cherry" and snatched it up. Fredric Taccone went through it for me and the thing sounded damn good, but I was never a fan of the cheapo alnico speakers they used...not for my style. So I talked about it with Fred, who loves G12H30s, as do I and I figured that might work (though neither of us had ever tried one in this kind of amp before). So I popped a G12H30 in there and boy...big improvement. I've had it that way since shortly after Fred went through it. But lately, I've noted that the highs were a little brittle/harsh, the lows were very present but there wasn't as much midrange crunch...and it wasn't breaking up as easily as I remembered my old R-o-R doing. I thought maybe what it needed was something a bit less efficient and a little darker. I just popped in a used Greenback and bingo--exactly what I've been looking for. Smoothed out the highs and breaks up a little earlier. Also quiets the amp down a few RCHs. Very cool. I attribute this to having hung around here long enough to be exposed to the concepts of efficiency and different speakers' personalities. And since doing so over the last few years, I've diddled with enough speakers, with a pretty analytical mindset, to have been able to make this prediction. But man...if you're not quite satisifed with your amp...you've GOT TO experiment a bit with speakers.