+1. BIG factor, especially the Hi Cut.adjusting the the lo cut and hi cut filter make a huge difference.
For my crunch I tend to use the Timmy with the gain ramped up.
Good point, the amp has a lot to do with how pedals react, my JSX clean channel didn't take overdrives well either. With these amps though, overdrives aren't really necessary anyway.I had a 5150 III 50W for a while and I never had any luck with OD pedals in front of the clean channel. This was with my FX8, a real Timmy and a real TS9. It could be that I never found the right OD, but I just don't think the clean channel on those amps takes drive pedals very well. I love the FX8 ODs (TS, Timmy, Eternal Love, Esoteric ACB/RCB) in front of my other amps.
You might try experimenting with the Bias and Sample Rate in the Advanced parameters. Lowering the Sample Rate to @20,000 Hz has helped the feel of a couple of the drives for me. Lowering the Mix can help the feel as well. I'm presuming you've tried other Clip Types, if not give others a try.I've tried TS808 + Fulltone OD dialed in different ways but not 100% happy with the results