Thanks!

While AAC is an improvement over mp3 (better sound for the same bitrate) it is worth noting that not every music player can play the AAC format (although it is not too bad) and that it is a proprietary format again... But it certainly would be a nice direction to head for...

But (as mentioned in the post) as bandwidth & storage become less of an issue it would be even better to use some lossless compression to even get better sound!