Thanks, this is good info. I do have a Mesa D800+ that adds a touch of warmth that I like. I was going to get the Aguilar TH preamp to mate with my Crown XLS 2502 power amp. I already have a MXR 81 for the Fender Jazz and Ray4 for a slightly cleaner sound. Can always pick up a TH preamp if I determine I need one. I still need to play around with the Carvin and Mesa heads to see what I get out of them with my basses and cabs before jumping on to a TH preamp.
The TH preamp is a fatally flawed product IMO. The TH magic is finding the right blend of gain and drive that gives you the amount of warmth and grit that you're after. The preamp doesn't have a drive control that you can dial in, it has a drive circuit you turn on or off. the off setting is, well, off. the on setting is too aggressive to be usable unless you really want a light version of overdrive. the magic is somewhere in the middle, where it starts to roll off some lows and some highs, and saturates the sound but before it sounds like an overdrive pedal. I would recommend buying a used TH500 and using that as a preamp, or a 350 to use as a DI box, vs. the pedal. and then you have the bonus of an extra head around if you need it.