I think the sound getting scratchy is due to a buffer underrun, and opcode is working on that for the next release, but this one has been hard to track down. Opcode is the guy that originally ported mame (mamex) before he left the project to superfro. I'm just a tester, I don't want people to think I have a hand in the code, I couldn't code my way out of a wet paper bag. The sound problem is present in a lot of roms and it's already reported...the team knows and they're working on it, so don't bother reporting that one.
If you want to help, let the mameox team know if any roms cause mameox to crash (usually a hang after loading complete) - there is a db in the works with a web interface for reporting rom status in the release levels, but for now, check the bugs on the sourceforge site (linked multiple times in this topic) and if a rom doesn't load for whatever reason (even the ones reported below), report it as a bug. If it's out of memory that's not a big deal but it will have low priority. Check some of the other bugs reported for examples for what info to include (I've put a lot on the page, look at one of mine that is marked in white - low priority).