This is from the popular and enduring 1924 operetta "Countess Maritza."
Fred Rich's Orchestra is another of those that enjoyed stays by future musical luminaries such as Bunny Berigan and Tommy Dorsey, don't know who the players are on this 1926 recording.
Do you know if this recording was from the Broadway run of it? (321 performances from 18 September, 1926 to 25 June, 1927 at the Shubert Theatre.) Because of the recording date you provided, I thought this might be the case.
That opening melody on the violin is from Pablo Sarasate's 'Zigeunerweisen.'
There's also a couple other classical melodies sprinkled in there. Added to what you mentioned, I agree that it's an unusual but very interesting recording.