On track 8, Toccata, Adagio & Fugue in C major starting at about 3:08 and continuing on to about 3:26 there is some low bass that is very subtle/subdued.

If you are not paying attention you can almost miss it. I am curious to know if it presents the same way on your system.

Yes, I think I know what you mean, and agree with your impression. It was played/recorded that way. I'm not sure what the music actually calls for in that passage; I don't have another performance to compare at the moment.

Interesting. With lower bass notes my expectation was always that there would be more 'presence'. It is quite surprising how soft/subtle those notes are.

Fred, I had some items due at the library today, and while I was there I picked up a Bach organ CD by Michael Murray on Telarc. It also has BMV 654 and on that segment a little over three minutes in, the low bass notes are just a bit more prominent, but not greatly different. By the way, I'd assumed that your track 8 reference was a typo, but we are talking about BMV 654?

Well, the 3rd part thereof I guess: Fugue

Okay, that wasn't what I was listening to; I'd just started a little over three minutes into track 1, which was still the Toccata.

Going to about 14:13, three minutes into the Fugue, I did hear some quite low level deep bass, but that isn't really unusual. It didn't sound very different in the same segment of the Murray disc.

I think I know why the confusion over what we were talking about. I ripped mine to Media Monkey and I suspect it split BMV 654 into 3 parts, resetting the counter.

Either way, I was surprised at the subtlety.