I think Solti's LSO Ninth is vastly superior to the Chicago remake, relistening doesn't change my opinion. It's not the just that the harsh, overly bright sound is bad in the latter. Solti had the remarkable ability to be loud and crude without ever being exciting as well. Moments such as the big climax of the first movement, the fast waltz in the second, and much of the Rondo:Burleske are fast and noisy, but also lacking in impact and focus in terms of balance and rhythm. Of course the playing as such is very fine for the most part, but with all due respect to John, the calibre of major orchestras today is so high that most play big, complex works extremely well. How much credit should go to the conductor, and who much would the orchestra have done anyway, for anyone?
I think conductors today get far too much credit for the excellent training and professionalism of the players, and I say this after several decades of orchestral playing. For me, the key question is what unique or significant insights does the conductor bring to the table--and I don't mean those little differences that invariably distinguish one performance from the next. In my view the answer here is "not many." I happened to see Solti and Chicago perform the symphony live around the same time as the recording was made--it was one of the most disappointing concerts I have ever attended, and to that extent the recording certainly is better, but hardly among the finest out there. For the record, here are three "sleeper" Mahler Ninths that I think are extremely, even unexpectedly excellent, and which have some very special moments that you won't find anywhere else (and all are demonstrably more interesting that Solit/Chicago):
Pesek/Royal Liverpool Philharmonic (Virgin)
Ozawa/Boston (Philips)
Masur/NYPO (Teldec)
Best,
Dave H