Rock: well recorded bass...60s/70s

My personal favorite is Can where in all theri albums no exception the bass recorded and sounding top notch-- Holger Czukay or Reebop Kwaku Bah(played in Talking heads as well) on bass.
Certainly Talking heads -- Tina especially in the album Stop Making Sense
Rich bass is also heard in Van Der Graaf Generator, but from the Hammond organ instead of guitar or string bass
Stray Cats -- love that string bass dontcha?
David Sylvian and Japan with Mick Karn on Fender bass -- nearly all of Japan and solo David Sylvian albums have rich and deep sound of bass. I admit the band is kinda jazzy, but still considered to be art rock.
Finally why not Pink Floyd DSOM or Momentary Lapse?

A lot of recordings in the 60's were unable to capture a clean bass tone. Some of it was due to the hardware used, while others was due to the engineer. Nothing on the playback end can correct for this!

Loomis, Bdp - Ah...OK, understand the context. Well, as they say, "there's no accounting for taste." I came of age late 60s/70s...lived through and survived them and (perhaps surprisingly) recall quite a bit from those years. Was a fan of Prog before it had a name. Was introduced to Yes & ELP by musicians who apparently liked both bands quite a lot. Being classically trained myself, I've always been attracted to music that blended rock with classical elements (e.g., Procol Harum). So, Loomis, w/respect to your (d) - you sort of do now. This is certainly not to say the genre didn't have candidates ripe for and deserving of balloon popping. I'll point out, however, that bands like MC5 (Kick out the Jams) and Blue Cheer (Parchment Farm is all you need to know) were Yang to my Prog Yin during these years. Didn't know I couldn't like both genres. I do get the reactionary elements behind punk but I'll take musicianship and musicality over attitude most days. If I want attitude w/music, I'll watch some videos of early Stones. BTW - Tales of Topographic Oceans might well be a terrible title but worse, the music is just not that good.

If you've not read it before, you might find the article at this link interesting.
History of Prog . Makes similar points as the two of you do.

Go check out The Nines' self-titled LP "The Nines". The one with Sun Don't Shine as Track 1. Digital only, I'm afraid. Crank it up. (Wish the drummer were better though).

Ha---Blue Cheer! Considered the worst Group we had ever heard. Painfully poor musicianship, laughably bad, with no redeeming qualities to counter-balance that failing. The lamest version of "Summertime Blues" imaginable. The Who's wasn't very good either, the great version being by the unlikely original version of The Guess Who.

I loved (still do) Procol Harum, and what made their "Classical training" (mostly on the part of organist Matthew Fisher---responsible for the Bach motif heard in "A Whiter Shade of Pale, rather than pianist Gary Brooker) different from Progressive Groups ( I don't consider them as such), was that they didn't flaunt it. They used their knowledge of music theory to write their songs and create their parts, not performing Classical pieces as a Rock Band, a bad idea IMO. "Pictures at an Exhibition" performed by a Rock trio? No thanks, ELP.

One of the bands I had never heard of, that is considered "prog" is "Patto." The first self-titled was released in the U.S. on Vertigo and is pretty kick ass sonically and musically (in fact, the US pressing is a bit less 'polite' than the far more expensive UK pressing and that works very effectively with the music). Their second album, Hold Your Fire, has some wonderful music- Ollie Halsall was a gifted guitarist with a vibraphonist's touch. The UK pressings are now astronomically expensive but the US copy (on Paramount if memory serves) does not lack for bass.
Some of the prog 'folk' is also amazing- John Martyn's Solid Air, the Fairport albums during the Denny-Thompson years (3 in one year), i don't know what to label Roy Harper's Stormcock, but it is magnificent, and he was a huge influence on Ian Anderson, Zep, etc.
The first ELP album is one of the cheapest pink labels today and one of the last, before Island switched to the pink rim. It is a pretty cool time capsule when you are in the moo(d)[g], but does sound dated now.