Im currently playing an Ampeg SVT3 Pro head along with 2 Mesa/Boogie cabs 1 x 15 and a 2 x 10. Ive been playing 2-3 times a week for the last 5 years through this rig and have always been happy with the sound. Recently I noticed my amp seemed like it wasnt functioning at 100%, so I decided to demo a SWR SM-900. Id done a lot of reading on various message boards and had only ever read positive reviews of the SM-900. I played one night using the SM-900 with my Boogie cabs, and I was really disappointed with the sound I was getting. It seemed like the amp wasnt producing the power or clarity that my Ampeg produced (even functioning at less than 100%). I had to play the SM-900 at a much higher level than my Ampeg to produce the volume of sound Im used to. This really confused me because the SM-900 claims to produce 900 watts @ 4 ohms, while my Ampeg is rated at only 450 watts @ 4 ohms. While I was disappointed in the performance of the SM-900, I wasnt ready to give up on it because of all the positive feedback I had read about the amp and because I was playing it in a room I was unfamiliar with. I decided to try the amp again in a room I play weekly, so Im very familiar with the acoustics. This time I took both amps to the job to hear them side-by-side. I set my rig up so I could easily switch the speakers from one amp to the other, and I played through each amp, switching back and forth several times. I was surprised to find that the Ampeg produced a punchier, cleaner, and louder sound. Again, Ive only ever read and heard rave reviews of the SM-900, so I started asking around to find any information that would explain the results I was getting. The only info that made any sense to me came from a bass player who owns several rigs SWR, Eden, Ampeg to list a few. He told me he loves his SWR rig, but ONLY WITH SWR CABINETS. Im not big into the technical specs of amps. I know the basics but pretty much rely on my ear to determine how I feel about gear. He explained that SWR tweaks their amps to run at a slightly different ohm rating, which the SWR cabinets are built for. This is why he says the amp sounds great through SWR cabinets. So I am going to try the amp with SWR cabinets probably a 1 x 15 and a 4 x 10. BUT MY REAL QUESTION IS: Is he right regarding the SWR gear? Its possible Im setting the amp up incorrectly or I picked up a defective amp to demo. Any info would be helpful. Thanks!!!