Minidisc used Atrac lossy compression. Better than lower bitrate mp3, but not as good as higher bit rate MP3.
Cassettes:
- Pre-recorded ones are poorer than best home HiFi cassettes because they are recorded at high speed.
- Cassettes are 1&7/8 ips. So getting more than 10 kHz upper frequency is challenging. More than 12 kHz is rare.
- Stereo cassettes are using less than 1/32" of a track, about 0.6mm, (1/8th inch tape, four tracks and guard band), so are very poor S/N
- Standard cassettes have also poor dynamic range.
- Cassettes are limited in bass response
- Cassettes have wow and flutter (varies according to equipment).
- Cassettes have more distortion than 256k mp3 and vinyl due to non-linear magnetic recording.
- Almost no pocket player supported Chrome or Metal formulations properly.
- If recording bias on cassette is increased the distortion is lower and frequency response may improve but dynamic range is reduced.
- Cassette tape recordings are worse with age or playing (wear, demagnetising, print-through).
- Dolby reduces noise (hiss) but adds distortion. Can be much worse "loss" than 128 k mp3
CD and wav format are lossless.
Minidisc is Atrac, not lossless and poorer than 256k mp3. MP3 and other digital compressions vary in quality according to encoder quality and bit rate.
Vinyl and tape have analogue losses (noise, frequency response and distortion) and mp3 can be better than vinyl or cassette. The higher speed 1/4" tapes can be better than vinyl, inc Elcaset (brilliant but too late). Most cassette tapes don't come close to vinyl quality. CD beats vinyl on noise, dynamic range, and distortion. Also effectively on frequency response after a few playing, but the upper limit on CD is beyond hearing or any content.