Bob's 60's recordings are much better sounding than almost all of his subsequent ones (one notable exception being Planet Waves, recorded in late '73 with The Band at Village Recorders in Los Angeles, released in early '74. It has just been released on LP and SACD by Mobile Fidelity, and sounds like the microphones are plugged straight into the recorder, played and sung live, with no overdubs and very little electronic enhancement), made during the time the art and engineering of recording was heading in the wrong direction---solid state boards, mics with "tailored" responses (the Shure SM57 and 58, for recordings? They were designed for live vocals, with a built-in presence peak to aid intelligibility on stage), many, many "effects" boxes (limiters, compressors, expanders, electronic reverb and echo, phase shifters, equalizers, etc.) inserted in the recording chain, and finally "new school" engineers taking the place of the dying and retiring WWII radio engineers who had Hi-Fi standards in recording and reproduction. The new school "engineers" fidelity standards are relative, not absolute.
The worst sounding Dylan albums are those produced (and engineered) by the worst-of-the-worst, Daniel Lanois---Oh Mercy and Time Out of Mind. TOoM sounds like the music is coming through the wall from the next room---one of the worst sounding albums I have ever heard. And it garnered Dylan his only Grammy! After Lanois, Bob started producing himself, as "Jack Frost". Much, much better.