Tweak audio playback on RP2

[tannewt]

This will hopefully make it more reliable. I think the failure to play was due to a latent interrupt from the previously interrupted playback.

[gamblor21]

Code looks good. I could not get the audio to fail in my testing. I'll approve and up to you if you want to wait for anyone else to try to "break" it.

Thanks for the fix! I know from experience how crazy chasing audio race conditions is.