I'm looking recommendations for a basic effects module or pre-amplifier for a five-string solid-body electric fiddle which has no on-board electronics.

The instrument is by Ashbury - I bought it new about eight years ago. It has no active electronics on board (nothing more active than a "tone" knob, anyway). I use it mostly for "silent" practice, and it's fine for that, but just sometimes I've had occasion to play it through an amplifier and have found its tone unacceptably harsh. I'm resigned, I think, to buying a pre-amp or effects box to do the job which the body of an acoustic instrument would do for me. In other words, I'm not after exotic effects (with one possible exception), but I'm looking for something to make the basic sound "warmer" and "rounder". Does anyone have any good recommendations, please?

The one special effect I'd like to have is to lower the pitch by an octave, so I was interested (and grateful) to see a separate forum topic on that very subject. The Line 6 POD xt mentioned there clearly offers much more than just an octave effect. Is there anyone with an opinion on whether it would also be a good route to the additional "warmth" and "roundness" I'm seeking?

Thanks in advance!