Settings for a V-twin rack through an F-30

[markblasco]

I just picked up an F-30, and I have had a V-twin rack preamp for a few weeks. The cleans on the F-30 are great, but I am not digging the distortion at all. The V-twin seems to have more of the heavy sound that I want. I am planning to use the F-30 for it's power amp and speaker, and bypassing the preamps in it altogether to use the V-twin.

Does anyone have any suggestions for setting on the V-twin? I am looking for anything from medium progressive metal to Opeth type heavier Metal.