I don't know which is worst, that I can't seem to find any sort of extensive, quality recordings of Andy singing outside of the series; or that it's taken me this long to even think of looking.
All I can find is a copy of his rendition of Lady Marmalade
And, "It's Not Easy Being Green,"
Both of these come from the same episode of Angel, "The House Always Wins". On the upside, both seem to be good quality and don't include the audience. Anything else, at best, is at a fan event and low audio quality, lots of cheering (naturally). It almost seems like a crime again nature for such talent to not only have been lost much, much too soon, but that no one had the sense to capture more of it on while they had the chance. It actually kind of makes me sad....
“In the game of chess, you can never let your adversary see your pieces.”