The day after the UL501 arrived I took it to rehearsal. I had some issues with lost signal. I had other heads with me and tried them out. Only the UL was cutting out. Contacted seller and he was genuinely concerned and willing to do whatever it took to make things right.
After further testing, the issue turned out to be a loose connection to the speakon connector. Still not positive if the mis-connect is on the amp or the cable, but now that the problem is diagnosed, I'm completely satisfied with my purchase and would positively recommend trading or buying here!