In reply to:

Can you set presets that allow you to set different channel levels, and switch between them with the remote on the fly? For example, preset A has the sub on +5, preset B has the sub on -3, and you can just hit a button on the remote



Yes you can.

In reply to:

and you can just hit a button on the remote(no gui needed) to drop the sub level quickly.



No. From what I can tell you have to go through the menu.......but keep in mind I'm still learning this thing and I have yet to open the manual!