I have the upstream amp 2.1 that I am using in a diy portable speaker. The subwoofer volume is very low and un-adjustable. I actually have 2 of the same exact setups I have the subwoofer in its own box that I connect with added banana plug terminals. Both subwoofers work fine in one setup, so I know it’s not the subwoofer wiring. I re - ran the wire going from the sub-out on the amp and that didn’t change anything either. All knob functions seem to be working. The led indicator blink with each click and I hear the beep as well. I do have the ACP workbench. I have not installed it yet though. Any thoughts from anyone?