I'm curious, you say small dropouts and you listed VLC as the playback software, any chance that the interaction between VLC and new OSX could be the root of the issue? Maybe VLC had the weird dropout and it's not related to your mac system at all?
Then off topic, how come you chose VLC. I do like that program and in fact talked the college where I work into installing it on all classroom computers since it will play ANY video no matter how old it is. Bottom line is I got tired of getting called to classrooms to figure out why some old ass piece of software an instuctor was using wouldn't work. We'd just intsall VLC and poof everything is fine but since the school uses imaged drives the instal goes away at shutdown. I digress, but I never thought to use it as an audio playback and wondered why you ended up using it.....
OK sorry for hijack.........back to USBPRe2.....
I have been using mine with the 15dB pads on all the time now after having some issues with clipping onstage mics with really loud bands. anyone else notice the clipping issue?