Agree about the early ‘70’s. 1970 and ‘71 have some darn clear sounding recordings. I so wish it didn’t take the crew almost 6 months after Bear went to jail to get it together and start recording without him or we’d have more from ‘71. And yep, ‘73 and ‘74 are distinct. Clear, bold and up close sounding.
There are certainly better sources than others for some shows and limited with others but far from all poor sounding. If one isn’t used to audience or raw soundboards then stick to the officially mastered multitrack release. We’re not talking Chesky here, but darn good for what they are... All ya need for the Dead is a linear balanced system with good organic flow and the music will do its magic regardless of recording quality (to an extent).