"breathtaking playing of the Chicago Symphony"
You mean all the large breaths the CSO brass players had to take to maintain all those endless fortissimos?
Yes, they had incredibly loud and tight sounding trumpets and trombones, but those Geyer horns turned hard and 'bracky' sounding while trying to keep up - almost like hearing more trombones. I never thought their woodwinds were all that great - certainly no real competition with Cleveland, Boston or N.Y. And the CSO percussion - with the exception of timpani (which were always too loud under Abbado and Levine) - never bothered too keep up with all that noise from the brass. I always got the impression that Solti didn't particularly like percussion.
For me, the Solti M8 is THE most overrated Mahler recording of all time. "Overrated" doesn't mean bad - it means what it says. The best sounding one of the lot was M7, recorded at Champagne-Ubrana, but the finale is a total 'train wreck'. M5 and M6 are decent albeit fast throughout. The digital M2, M3 and M9 are all horror shows, both musically and sonic wise. So if you mean that everybody starts together and ends together, and that there are lots of in-tune loud moments in between, then sure - I guess they're great.
Towards the end of Solti's reign I saw the CSO do M5 in Davies Hall. It was awful. The cymbal player had about five pairs of plate cymbals spread out on a table, all of which sounded just the same as the last pair, and with the result that it sounded as though he had just picked up the wrong pair. Gordon Peters - in spite of being the great musician and conductor that he was (Chicago Civic Orch.) - completely underplayed the bass drum in relation to everything else. The tam-tam was consistently underplayed (can't do that with dark sounding Wuhans). Arnold Jacobs was toward the end of his run. Clevenger's solos in the third movement were very hard and 'brackish' sounding (as described above). He did sound fine as long as he was playing less than fortissimo. The strings were NOTHING to write home about, even in the famous Adagietto. Solti himself was beyond atrocious.
I don't know, I think Solti's best Mahler days were his early Mahler days - before he even got to Chicago. Some say he tried to copy the VPO brass sound in Chicago. Others have said that the CSO brass section tried to hear themselves by bouncing their sound off the back wall. Both sound like excuses to me. Nothing I've heard from Solti sounds as good - to me - as what was put down on tape with Kubelik, Martinon, Stokowski or Morton Gould (not to mention Reiner, of course)
On Youtube, I've watched the Boulez/CSO M7 and the incredibly slow and boring Haitink/CSO M6. The playing is very good, but I think that hall just isn't good for works that require that large of an orchestra. Everybody is spread out in a very wide configuration, with not enough front to back depth. As result, the brass sound as though they're sitting right up front. I don't know, I think they should experiment placing the horns in center and across the very back, separating the trumpets from the trombones in the process (their a bad influence on each other) - and make the trumpets play German rotary valve models.
I often wonder what the Solti M8 would sound like if it had been the VPO instead of the CSO. It would have had more out-of-tune playing, yes, but the sound of the orchestra would certainly have better matched the soft edge singing of the Viennese choirs. As it stands now, there's a real disconnect between the perfect but 'hard' playing of the CSO, and the softer sounding choral forces (the dubbed in organ is also out-of-sync at one spot in Part I).
By the way, the tam-tam is great on Solti's CSO "DLvdE", but that's because Gordon Peters played it and was using Fred Beckman's own dining room tam-tam. Fred Beckman was the person who first imported Wuhan tam-tams from China and sold them to pretty much every major orchestra in American, including the 50" (130 cm) monster that Pittsburgh drags out from time to time. Too bad Yvonne Minton isn't a bit better on that one.