Oskar Fried and the other by the more well-known-but-getting-obscure-by-the-minute Paul van Kempen. Both were conductors who were well established in their day and whose recordings have been sought after by collectors for years.

First up, a 1927 (early electric so it could be 1926) recording featuring Oskar Fried and the Berlin State Opera. I believe one of the first recordings of the Nutcracker done by the electrical method. And the second, a 1939 recording featuring the Dresden Philharmonic conducted by Paul van Kempen. Both recordings were made for the Deutsche Grammophon (Polydor) company. The Fried was issued in the States on the Brunwick label and the van Kempen was probably not issued overseas as war broke out shortly after the recording was made.

(Paul van Kempen - less obscure but no less collectable)