I have had this same exact problem for about 4 years now. I keep checking online every few months but never have any luck. What gives? Is there nobody out there that can program an application to transcode efficiently while maintaining metadata including album art?
I bought and owned over 1,000 cd's by 2003 when I decided to rip them all with WMP (Windows Media Player 9) on a PC into WMA Lossless without DRM (Digital Rights Management). I used the slow but detailed error correction so it took a long time to complete this project. Many of the CD's were from different countries (as I had been living in different countries) so some had different songs and album art than the US Versions. As a response I had to continually over-ride the built in suggestions for metadata from WMP and had to manually type in song titles and search for album art online, then copy and paste it into the folder the files were in. WMP would then import that file into the WMA metadata. It took a lot of evenings but it was worth it and I had the best music collection I knew of while traveling for another 5 years. I was ahead of the curve as far as digital music went.
In 2008 I switched to a MacBook Pro and haven't had easy access to my music collection sense. In 2011, I ripped another batch of about 150 new CD's I've bought into Apple Lossless but now have to keep 3x music collection folders. 1) WMA Lossless, 2) VBR MP3 (converted for itunes without art), and 3) Apple Lossless. I have thought about switching back to a PC but I do like my mac so I'm stuck with no options.
There are very few applications that can transcode WMA Lossless to Apple Lossless, less that can do so without bloating the file size to almost double, and none that keep the size similar to WMA Lossless while maintaining the album art already saved in my music collection's folder hierarchy. (To clarify itunes on mac doesn't, Flip4Mac doesn't help, Auditri does not, VLC does not, Song bird does not, Pro Audio Converter does not, easyWMA does not. I've even installed VMware (virtual machine to run Windows on my mac) to try dbpoweramp and no luck.) And with all these trials I've also noticed it takes just as long to transcode on my Intel i5 MBP as it did on my AMD Athalon XP PC in 2003.
I'm very confused so any help would be greatly appreciated.