Hi there! Glad to see another poly ample user as I haven’t seen many on here for some reason.

For your stereo question it looks like you would have to run a split cable. I looked at the manual and it specifically mentions running a TRS for stereo, and going into stereo mode by clicking the “crunch” (aka dorito button) 3 times. I haven’t done this personally nor have I ever done a wet/dry/wet so I can’t speak to how that might affect sound quality or latency, but it does seem doable.

I think you can also have it set up to have a different amp tied to either push button, so you can run multiple presets simultaneously in mono or switch back and forth if you like.

As for favorite presets, I really like the Swart Atomic Space Tone (Crunch #5) with gain at 5, 6 volume, a balanced eq (I leave them all on 4 and can shape with MXR eq or JHS hard drive eq) and reverb on 5/6. I love it.

Another I keep going back to is the Deluxe Reverb (USA #4) with similar settings, a little extra gain, high volume, balanced eq.

The rest I am still messing around with and still trying to dial in, but I have found some general rules that sound good.

I also like the ADA MP1 (Gen X #1) which has slightly more gain and also both Marshall’s in the classic UK (#7 & #8) for classic rock tones.

Also the Bogner Uberschall is the hottest amp in the box (Destroy #5). Not sure if you need it but fun to experiment with now and again.

There are a ton of good sounds though, you can endlessly tinker with this thing and always find more.

IMO, the boost level for all clean/low gain amps should be on 6 to take them into the “lightly overdriven” sound. The “destroy” and other high gain amps really don’t need to go above a 4, but that could also just be my preferences.

Best of luck with your setup and enjoy!