I have a 2007 era Macbook Pro that I use in a project studio for editing with FCP and Audio Production with Protools 10 and other various software. I recently had one of those cheaper BUS powered Lexington Alphia USB Audio I/O interfaces to power my KRK monitors. It worked fine with exception of a small buzz out of the left channel. However I upgraded to a Protools MBox Mini 3rd Gen and it was just outputting terribly distorted audio at any level. So after an hour and a half of a remote controlled service call with Avid I set up an RMA to return it.. at my expense to the retailer. I was frustrated that I had to pay to ship back something sent to me that was broken... so I said what the hell and tried it on my 2010 unibody macbook and it worked fine, worked fine on my Toshiba Windows 7 box as well. I meticously sifted through the Avid Audio forms for hours trying to find an answer... I saw someone that had the same issue and solved it by passing the MBox through a Powered USB Hub... so I said what the hell, I'll try and it viola... it worked. After more research I've come to find out my MBP had an issue with weak/unstable usb power output... So my question is, do you think I'll have any luck with better bus power coming out of a USB Express card? Does anyone have any recommendations on a good card for my MBP?