Does anyone have any experience using Media Monkey to synch with the new Sony Walkman NWZ-A826K?
I can confirm that Sony Walkman NWZ-A829 (which is probably the same as 826 except for the memory size) works with MediaMonkey, with very small caveats; it is treated as MTP device. Songs, playlists and cover art sync well. It is fairly quick, too (not quite as quick as drag and drop, though).
MediaMonkey will not recognize songs that are already on the device (for example, if you placed them there through drag and drop from Windows Explorer); you need to delete the files from the player, add them to the MediaMonkey library and then sync the player through MediaMonkey's interface; then, songs and playlists will sync with no issues. In particular, I have a bunch of .m4a files and I had no luck with playlists using any other software (and I tried several); some would not be able to create playlists with those files at all, and some could be coerced (kicking and screaming) into creating playlists on the computer, but they would not sync them to the player (and copying them using drag and drop is useless). MediaMonkey does it with no problem and no special consideration is needed, just use the default settings.
Cover art works if it is embedded in the files (that's the standard way and the default in MediaMonkey). The non-standard way - trying to associate the song files with a picture file in the same directory - looks OK in MediaMonkey, and it will copy the picture file to the player, but the player will not recognize it as cover art. The size of the pictures is generally small, so they do not add that much size to the song files. It worked almost flawlessly; the only issue was that for a small number (3 out of 270) of albums, the Walkman would not recognize the cover art properly. Looked like a picture issue, as once I switched to a different picture file, it worked fine.