Wrote this up on reddit for the Vita RetroArch prBoom and to my pleasant surprise, it's been useful to people, so here I go:
This assumes that you already have a recent (hopefully the latest) nightly of RetroArch's prBoom VPK installed. If not, here ya go http://buildbot.libretro.com/nightly/playstation/vita/
1. Download faithful MP3 conversions of the actual music from http://sc55.duke4.net/games.php#doom
2. Use a batch file rename utility (NOT meaning a DOS style .BAT, just to be clear) to remove the "d_" (minus the quotation marks) from the beginning of each MP3's name.
3. FTP the renamed MP3s over to whatever folder on your Vita you put your Doom IWAD files (making sure that prboom.wad is there as well).
4. Boot your prBoom bubble and the music should Just Work. OPTIONAL: Say thanks if this enhances your experience, please
Here's the post on reddit https://www.reddit.com/r/vitahacks/comm ... st_doom_1/
NOTE: May or may not work with a PSTV. I don't have one to test on.
NOTE2: I am usually a lurker (rather shy IRL), so don't expect stimulating discourse from me.