in general i would say that the stuff breaks down as follows:
- live versions of officially released songs -- these naturally vary a great deal depending on performance and recording quality, and should be measured against officially released live material such as that on the live albums and the quine tapes;
- live material not otherwise officially available -- these vary quite a bit as well, but some of it (such as "the nothing song," see below) immediately strike me as being essential listening;
- demos and rehearsals -- much of this stuff has since been released on the 5CD peel slowly and see box set, but again some has not and is quite essential (see "loop" below);
- live, studio or radio broadcast performances of post-VU material -- lou reed solo, velvets reunions, etc. -- that is generally not essential;
- interviews -- some of this stuff is interesting but not necessarily worth listening to more than once; some producers of these unofficial releases have mixed interviews in with live performances in a way that does not make them very interesting or accessible.
searchin' for my mainline is a 3CD set that contains the following essentials. "loop" is a fantastic feedback drone/phase piece that was recorded and released in 1966 as the locked-groove b-side of a flexi-disc that came with the magazine aspen #3. of course, ubu.com has the file here (scroll down). this recording is crucial to the history of feedback, far moreso than the beatles' "in my life" and perhaps second only to the "fontana mix - feed" of max neuhaus (also 1966). disc 1 also features an acoustic version of "heroin" credited to "rehearsal, paris 1/25/72" and is unlike any version i've heard before. disc 2 contains live versions of "what goes on" and "run run run" from the hilltop rock festival, rindge, new hampshire, august 2, 1969 (my second birthday!) that are absolutely smoking: "run run run" in particular contains some of reed's most blistering feedback-drenched guitar soloing ever, second only to his work on "i heard her call my name" which is of course one of if not the greatest rock guitar solos ever.
the two middle discs of the caught between the twisted stars 4 CD set are most noteworthy. disc 2 features "the nothing song," a nearly 30-minute mid-tempo trance-jam soundtrack recorded at an exploding plastic inevitable show at the valleydale ballroom, columbus ohio, november 4, 1966. essentially during a typical EPI performance of the time, the VU would provide live instrumental accompaniment to the multiple andy warhol films that would be projected simultaneously before doing their own set (which of course also involved film projections, often of the band members' faces for example). like "loop," "the nothing song" taps into the lamonte young drone minimalism that john cale helped bring into the band's sound, in this case also featuring processed vocals from nico that float hauntingly over the proceedings and give the piece an eastern feel. disc 3 also goes in for extended jams, clocking in not only with a 25-minute "sister ray" but also with a 39-minute version of something called "sweet sister ray" which, as the title suggests, was performed as a mellower and (if i recall correctly) largely instrumental prelude to "sister ray" proper. all essential listening for a full appreciation of the VU's music.
finally, a walk with the velvet underground runs 5 CDs. this set features what i believe are pop songs lou reed wrote for the pickwick label that were recorded by other bands before the VU formed, as well as the infamous songs "sneaky pete" and "(do) the ostrich" recorded by the primitives, an early reed-cale proto-VU. there is also a more complete (6:49) version of "loop" (still a shorter run time than the version on ubu but i've not compared the two). there are a lot of demos and mono mixes here that are either inessential or otherwise available. there are also recordings from EPI performances and warhol movies that, unlike "the nothing song," aren't recorded very well and have all the film dialogue mixed into the track as well, which makes for rather muddied and/or pointless listening. there are some nice versions of "loaded" material identified as "robinson's apartment sessions" as well as some post-VU live recordings, at bataclan (29/1/72) and fondation cartier (paris 15/6/90) but i don't know enough about these (except that the latter is obviously a reunion tour).
more to come...