I posted this in the Custom ROM thread I'm using, but thought it may help others. Hopefully the cross-post is forgivable. Ever since I got the Imagio, I've had constant issues with the HTC Music tab, primarily stuttering every few seconds during playback. WMP has always worked fine.
I did two things today, not sure which one did the trick, but I'm starting to think is was the second one, now that I really think about this:
1) I reformatted the microSD card with 4K blocks and re-synced everything. Block size shouldn't matter for files this size, so I don't know why this would have helped if it was indeed the reason.
2) I removed any tracks with special characters in the artist/title names. In my case I had tracks from "Blue Oyster Cult" and "Motley Crue", with the umlauts in the 'proper' locations. I have a Roku Soundbridge that doesn't like those tracks either, so I thought it was worth a try.
Anyway, I've been hammering this thing playing music all afternoon and only ran into a single instance where playback stopped/stuttered. It could just be a bum MP3 (sync issues do happen!). I have my full playlist on the device and it's really working quite well. AudioManager_eng.exe isn't spiking and staying at a nice steady 2-5% CPU. [Note: I am using a custom 6.5.x/SenseUI 2.5 ROM, but I had these problems with the stock VZW ROM as well]
If anyone else is having the stuttering/stopping problem every couple seconds on their device as well, I recommend trying the 2 things I did if you haven't already.
I will put the special character tracks back on the device before I next flash it to see if it causes the HTC Music tab to choke. I'm understandably leery to do that right now since it's actually working right for the first time