Right. Lossless would be decrypting the file.
But since that doesn't seem to be possible anymore, at least with most music services like Zune and Napster, the only real option is a lossy method - of which
SoundTaxi is quite great. Think about it: your source file is 192kbps WMA... if you save it to 320kbps that's almost DOUBLE the quality, so you shouldn't really have any issues.