A subtle gotcha with the A-PRO. It may appear to work fine connected through a hub. Ah yes..... but on my setup, regardless of hub type, the knobs and sliders behave very strangely. Specifically, once you move any of them above about MIDI value 70 or so, they start sending messages continuously. Then if you move them back, they stop. This is on Win 7 x64, not sure if this occurs on 32 bit systems as well. Just thought I'd mention it. You can clearly see it by recording to a track and looking at MIDI events. Damn nuisance because my laptop only has 3 USB ports and the UA25 and A800 are now demanding one each, because they CAN'T be externally powered. Yes, the A800 supports a power pack. No, it won't use USB if you connect one, only the MIDI ports. I have utterly no idea why, only some weird geek at Roland knows why they did that.