I've only had the SM500 for a month but so far I'm very impressed. Our drummer says that it's clear, he can feel it, he can hear it and unlike my old amp, it doesn't hurt his ears. (Imagine that? a drummer that can still hear!) There's nothing like being bathed in bass without it becoming obnoxious. The only way to describe it is that it's SWRvy. I have it paired up with the Goliath III 4 10" speaker cabnet. It sounded great but something seemed missing so I plugged in a cheap 15" bass speaker cabnet that I had laying around and WOW! It really rounded out the sound and filled in the cracks kinda like morter holding together a brick wall. So I immediatly orded the Little Bertha 15" cab. For my taste this seems to be the perfect speaker combination for the SM500. And then, just when life couldn't get any better, my old lady got the visa bill!

Overall:
Used this head for about 1.5 years and started to have problems with it. I would say that the tone qualities are fine (if you aren't looking for an SVT type growl) - smooth and punchy although it has that 'typical' Eden/SWR loudness button sound. My problem with this head was that it didn't hold up in the face of constant use. It started to cut out on me (overheating, I think, although the road case was very well ventilated). Also, there has always been some kind of grounding problem with the amp. Not sure if it is just at the Di out or what. Also, very annoyingly, the speaker cutout doesn't mute the DI signal, so you can't tune silently by throwing that switch. The cab will be muted but if you are running a DI line, your signal will still hit the fronts. This necessitates a separate cutout pedal. (Maybe that floor model white(Boss?) tuner automatically cuts the output when you step on it but I use a TU2 and it doesn't have that functionality. The knobs ten to fall off and the caps for the knobs also fall off easily. For the price, you should at least look into a dedicated pre-amp matched up with a used Crest or maybe QSC power amp, or whatever is your fav.