Since around 91 I've been playin 5 & 6 string instruments, tuned down up to a full step, Metal an beyond, thru an SWR SM-900, and a variety of SWR Goliath and Jr. cabs; IIs, IIIs, etc. In fact, my main rig at moment is my 900 an a Goliath Jr. The amp is stereo, an for rehearsals, tried runnin just one side of my amp. 350 watts, 4ohms. Power amp clipped, causin distortion, an possible speaker damage. That is how I define "underpowered". Why? Cuz when I bridge my amp, a hair over 800w at same 4ohms, no more power amp clipping, no more distortion. But, from what I hear in original post the problem sounds more gain oriented. First, if yer cranking yer bass' pre, check yer battery(s)! OFF-ten! Many weird distortion issues come from this. An EASY fix. 2nd, check the input gain on yer head. If crankin yer preamp, it is easy to overload the head's first preamp stage. Reduce yer gain, both on the bass by puttin eq controls ta flat, and the input on the amp. Then recover volume loss wit the master. I've never had real distortion issues, my bands continue ta tell me to turn down despite my mini rig. And third, many metal players prize distortion in their tone, as evidenced by the myriad of pedals an effects units on the market. Usin some fairly common techniques, you may be able ta learn to control it. Lastly, maybe if yer cab 8ohms, try a 4 ohm cab. Droppin my head to a 4ohm load w/single cab, adds fullness and headroom (along wit sustain bein the keys to great tones, imho), if not more volume. Try this an see, yer distortion issues could be one, or a combination, of above. Check the battery, reduce gain. If helps at all, experiment wit settings ta compliment yer playin an musical styles. Really hope this helps.
