This is what I found for the Marantz:
Product highlights:
plays CDs, CD-Rs & CD-RWs plus WMA, MP3 and AAC CDs
front-panel USB input (Type A) for USB flash drives
supports FLAC, WAV, AIFF, ALAC and DSD file playback
high-performance digital-to-analog converter handles high-res files from USB up to 24-bit-/192kHz (DSD up to 5.6MHz)
Depending on what you can get, maybe 24-bit FLAC or WAV at the highest sample rate. Not that you
need that, but why not? You can keep the best quality "archive" convert to any other lossless or lossy format later.
In case you don't know...
CDs are 16-bit, 44.1kHz, 2-channel stereo. A WAV or AIFF file with the same characteristics has the same audio data as the CD. FLAC and ALAC is lossless compression so you can get the same audio data when it's played and decoded.
And yes. FLAC and ALAC are about half the size and have better, more standardized, metadata support. (Basically, everything is "better" than WAV for metadata.)
MP3 and AAC are lossy compression. Data is thrown-away to make a smaller file. They aren't necessarily "terrible" and you may not actually hear any difference, but beware of the fact that they are lossy and if you later convert to another lossy format that's another generation of lossy compression and SOME "damage" accumulates.
...A lot of people rip their CDs to FLAC and keep a FLAC archive, then make smaller MP3 or AAC (or other files) for "everyday portable" playback on their phone or computer digital audio player, etc..