I don't know of a really discrete multichannel mix of the Mahler 3rd, which is a shame - the symphony uses a offstage instruments to great effect, especially in the third movement. I'd only heard the symphony in recordings and the first time I heard it live, at the NY Phil (not even in great seats), and hearing the posthorn solo in the 3rd movement come from above and behind me instead of in front of me was almost like hearing the moment for the first time.I've come to the conclusion that the music matters more than the format and level of discreetness, so when it comes to classical music, the performance and mastering is more important than whether the multichannel mix is slightly discrete or mega discrete. This Zander conducted-performance of Mahler's second symphony is relatively discrete but I'm afraid the performance just doesn't do it for me: it's simply too slow. My favourite symphony is Mahler's 3rd and I'd love to hear a mega discrete multichannel mix of a well-mastered first-class performance. I've got this box set of Mahler symphonies by Abbado-Lucerne Festival Orchestra that contains a fabulous 3rd symphony, but it's a live performance and not exactly discrete, so it ticks the right boxes...except the multichannel mix is fairly weak. Still, at least it's great as is
However, I do agree - I'd rather hear a great performance in good stereo than a mediocre performance in great surround. And a lot of SACD labels feature mediocre interpretations with mediocre orchestras, which is a bit of a bummer.
To bring it back to Dutton suggestions, I've recommended the Stokowski Mahler 2 he made with RCA, and I assume the Bernstein Mahler recordings are off-limits. Any other quad Mahler recordings that would be ripe for a reissue by DV?