Dennis Fodor wrote, responding to me:

>Brigitte Hamann's book _Hitler's Wien_, a standard work, offers testimony
>by two of Hitler's friends saying that they attended Mahler performances
>at the Vienna Hofoper in his company.  Both instances involved Mahler
>_conducting _ Wagner, and not Mahler being performed.
>
>The one dating, by Friend Rudolf Haeusler, is 1913.  The 1906 dating
>cited by Mitch is more obliquely treated by Hamann.  According to her,
>there 's a postcard sent by Hitler that seems to claim that he attended a
>Hofoper performance of Tristan on May 6 (not May 8).  She also writes that
>Hitler's friend August Kubizek in his memoirs claimed that he attended two
>performances at the Hofoper with Hitler, one of these having been Tristan.
>But; writes Hammann, neither Kubizek nor the Hofoper records give the name
>of the conductor of this Tristan performance.  None the less, Kubizek wrote
>that Hitler had "the greatest regard" for Mahler--as a propagator of the
>Wagner tradition.

De La Grange says that on May 8 (sic), 1906, Mahler conducted Tristan.
The next day, Hitler attended a performance of The Flying Dutchman,
conducted by Franz Schalk.  De La Grange adds that "probably" on May 22,
Hitler attended Lohengrin, again conducted by Schalk.

Mitch Friedfeld