I have that set, and noticed that too. Bugs me. Especially after i bought the set in hopes it would be better than the Milestones LP I have of the same recording. On the LP, Bill is smack in the middle, and it sounds great. After going back to the LP I find it to be really so much better than any CD's I have heard of that concert. Bass and drums are not as dynamic, but I don't miss that; there's some special ambient quality to the LP, as well as the mix being better. And the LP is a 1975 reissue!
Regards, Vince