I have a SWR SM-900, along with a Goliath III cab. The sound is naturally bright, but depending on what bass I am playing, can be even brighter than normal. I'm trying to figure out the best way to get more bottom end. I am considering adding a 15 or 18 speaker cab (something like a Trace Elliot). Would it help to add a preamp to the set-up? Does any one have any ideas as to other speaker set-ups, etc. that I might look at? Any suggestions would be appreciated. I actually like the Goliath III's, but I seem to be missing out on a lot bottom end. Thanks.