If Handbrake is the best solution to encode videos on the mac, MAX is the solution for audio files.

It supports a lot of formats, including CDs, detects album info, and offers solutions for the album art. The only problems I found are some issues with the GUI and Spaces, both drawers being overlapped, and the workflow being a bit weird.

I wanted to convert some FLAC files to ALAC (Apple Lossless) to add them to iTunes without losing quality. Here are the steps you need to do such kind of conversion:

1. Open Max
2. File > Convert Files and select your files
3. Max > Preferences > Formats, select Apple MPEG-4 Audio (YMMV), the + button, select lossless and, if you want, VBR.
3. Max > Preferences > iTunes > Add output files to iTunes Library
4. Select all files > Tools > Download Album Art
5. Convert (And you will find the results in ~/Music)

As you can see, this is not a linear workflow, but the result works. If I find the time, I might contribute to this project solving that problem.