I use an SWR SM-400S. I like to add a lot of bass to my sound using the preamp, but it winds up clipping. I can turn the gain down on the preamp, but I'd rather not. It has whatever brand 12AX7 SWR was using when it was manufactured. What I was wondering is whether or not putting in a new, better, preamp tube would help. If it would, what type of tube should I use? I can't afford anything much more than $30, so please don't tell me to go get a Telefunken. I was thinking about going with an Electro-Harmonix, but I really want to know if that would even help.