I'm in the market for a new, lightweight head, 600-700W into 2ohm. I want to keep the weight around 25#s, give or take a few. I don't mind solid state, or hybrid, but I can't stand the sterile sound of SWRs and the like. I don't need bi-amping. I don't need dual power channels. I don't need a lot of bells and whistles. And I don't want to hock the farm to buy it. I'm very old school in my tone preferences. I primarily use Fender P-Basses, and I always run a mute on the strings, under the bridge cover. Think Ampeg here on a long term scale (I've been using Ampeg since 1962 as my primary amps). I play Country and 50s/60s Rock and Rock-A-Billy. After a lot of looking, reading, checking specs, scouring websites and threads, I think I may have narrowed it down to a few. The new Genz-Benz 600 looks like it might be a contender. The Mesa M-pulse 600 is another one. At an extreme, the Fender Bassman 1200S might also be included, but I think it might be a little overkill. (If Ampeg ever releases the PB-800, it could be a contender as well. But that doesn't look likely.) But, I haven't been able to find them to play them. So, I'm asking for a little help here. What experience do any of you have with these two amps mainly, the GB-600, and the M-Pulse 600? Thanks for your help and inputs.