I think what you want to do is check 'Listen To This Device', and in your windows Mixer, set the volume of that recording device to zero. Then, open DriveLine, and adjust the volume in there. When DriveLine closes, it will restore the volume to zero for that audio line. I'm not 100% on all of this, because my girlfriend has my car tonight, so I cannot verify the exact setup.
DriveLine does not index your media files. It just provides an interface to add them to the playlist. You can definitely browse all music. And if your music folders are structure in an Artist\Album style, browsing artists is pretty easy. You can add as many songs/folders to the playlist as you like. My best recommendation is to just play with a bit, see how it works, and decide if you like it.
Thanks, that did the trick! Regarding the multiple soundcard issue, it seems it is a problem on all front-ends and for that matter for anyone wishing to send audio from different apps to different soundcards. Most apps don't support choosing which soundcard to use, they tend to just use the windows default. I solved the problem by using one soundcard as the windows default for DriveLine (music, navigation, etc) and dumping Windows Media Center for XBMC, which DOES let you choose a different soundcard than the default. Hell, I don't know why I was using WMC in the first place --- I guess just because the kids don't need anything fancy, just a way to watch movies.
Awesome. So are you square on the media player and playlist within DriveLine for playing media files?
Yeah, I get it. You have to build the playlist by adding music then "play the playlist". You can't for example, just play a song or an album or a single artist -- unless you add it to the play list first. And there's only one playlist, it's not like media players where you can build multiple playlists. All in all a nice fairly simple front end, and works right out of the box, unlike some of the other front-ends.