Lossless Music Is Too Big
A WAV album runs 500 MB. Lossy conversion is the only realistic slim-down — the question is which parts of the audio your ears will actually miss.
Lossless is the archive, lossy is the carry copy
Keep WAV/FLAC as the master library on disk or NAS; export lossy copies (MP3/AAC/M4A) for phone, car and sharing. The information loss is permanent — never treat a re-encoded FLAC as "restored".
Bitrate picks
192 kbps: blind-listen indistinguishable from lossless for most. 128–160: the everyday sweet spot, a quarter to a sixth of lossless size. 96 and below: speech content only. AAC sounds slightly better than MP3 at the same rate — prefer M4A when the device supports it.
Channels and format picks
Keep stereo for music (mono collapses the soundstage; it is a voice-content trick). MP3 for maximum compatibility, M4A for modern devices, OGG for balanced local storage. Spot-check cymbals and breath after converting — high frequencies fail first.