There are multiple Walter recordings of Bruckner's 9th, but if the one you heard was the studio recording with the Columbia SO on Sony, I would partially agree with you (although many revere it). This performance is best heard on Pristine Audio's restoration which reveals unsuspected energy. Even there, however, it doesn't rival, say, Jochum's 1954 DG mono recording (not his later DG stereo performance). I'd suggest trying Walter in Brahms, Mozart, Schubert and Beethoven Syms 1,2,3,4,6 & 7 (stereos).
Again, Pristine Audio's restorations are the best way to hear Horenstein's Vox recordings
(many reviewed favourably on MW-I).
Some years ago, Verbitsky's reading of Brahms 1st Symphony (with the West Australian SO sounding like the VPO) was the easily finest live performance of the work I've heard. It rivalled any recording known to me, including those by the acknowledged masters of Brahms interpretation: Furtwaengler, Klemperer, Walter, etc.
I'd add Menuhin and Alicia de Larrocha (especially on her Spanish HMV recordings) to the list of performers who 'speak' to me.
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