Hmmm....was the UA-25 USB only powered? I never really checked it out.
Supposedly yes (I think someone on here got one to work, but I'm not sure if they had a lappy behind it or not). After the UA-5, edirol produced a series of software driven USB/Firewire devices.
As you can see here UA-25 original, no power-in.
The EX has a ground lift which is a nice improvement, I have had ground loop issues with a UA25 before.
digifish