I know its nice to be able to stream from your mobile device but how about just using a good old fashion USB flash drive for the purpose of music. You can have full control on the i-drive, you can get up to 64GB+ of your favorite songs. Your mobile device is freed up and not using any juice. Relatively inexpensive way to get song to your i-drive. Just make sure its formatted to FAT32 file system and use special software for anything above 4GB because of Window's limitations.

4GB for $6 and some change and you're done!
Amazon.com: SanDisk Cruzer Fit 4 GB USB Flash Drive SDCZ33-004G-B35: Electronics