I'll give it a try. But I learned during the original problem I had with sound, root uses a completely different sound scheme than normal users in TDE. root makes use of alsa-raw which bypasses a bulk of the user sound config, so it may work fine and still not be a permission issue.
If true then file a bug report. There should be no reason why root should use arts differently than non-root users.
Since this is virtualbox, I'll just create users doug, sally, ben and jerry and have totally different profiles :)
At this point I say stop and test with real hardware. Virtual machines work great for many things, but your particular problem needs to be resolved with real hardware. Get a second machine, create a second partition. I use all of the above for testing.
Darrell