Karajan Mahler Six

That does sound very tempting!

At the link above, click on videos, then scroll down and click on the video entitled "The Original Source Series - The Making of Karajan: Mahler's 6th Symphony.

The Karajan recording of the 6th was my first introduction to the symphony.  
Very fine performance indeed. It captures the full emotion of the work.

There’s a Tracking Angle article/review by Mark Ward that’s very well written.

https://trackingangle.com/music/the-original-source-does-mahler-on-steroids