I think it depends on the amp you run it into. I run it into stereo Quilter Steelaire combos and I get wonderful results. That said, I ran it into the front end of my Boss Katana and it sounded horrible. As far as a tube amp, I don't know. I sold all my tube amps about 4 years ago. I would think the cleaner the amp, the better the results though. You want a flat response for the Helix or else the models might not sound correct.