Don't be so certain that wired is better than wireless when it comes to sound quality. After all, Spotify's top bit rate, 320 kbps, is only available to premium service subscribers. Otherwise, Spotify's bit rates are either 96 kbps or 160 kbps. You have to remember, though, that if you're using your phone's analog output, then the quality of the sound you end up with is, to a large degree, dependent on the quality of your phone's DAC.
Similarly, if you were a Pandora user, you'd have a variety of bitrates available (and this is from Pandora's Help page):
Pandora on the Web plays 64k AAC+ for free listeners and 192kbps for Pandora One subscribers. All in-home devices play 128kbps audio, and mobile devices receive a variety of different rates depending on the capability of the device and the network they are on, but never more than 64k AAC+.
I'd look for an external DAC solution that lets you either go wireless or use your phone's USB out. I can actually get a B&O DAC module for my phone, but most of what I read recommends using a different DAC than the B&O solution.