Old thread, I realize, but I'm posting in hopes of reviving the topic.
I have an old HTC Trophy running WP 7.5 that I think sounds pretty good for a smartphone (in part due to an SRS sound enhancer). I am looking to upgrade soon to either an HTC 8x or a Nokia Lumia 928 running WP 8 (Verizon customer).
My only hesitation about the Lumia is sound quality. I've read "good sound" on various reviews, but nothing that is especially informative. My spouse has a lower end Lumia that hasn't really impressed me in the sound department, although it does sound "clean" and would probably be OK if paired with a DAC/amp.