I especially enjoy these two tracks because they allow us an understanding of where 1930s musicians thought their music was going - both are self-consciously progressive.
In some ways, the predictions of the musicians here are prophetic, but in others these 'futuristic' ideas serve only to anchor the music in its era. Regardless of its modernity, this music is quality material played by quality musicians - surely more important than any discussion of progress in stylistic terms.
Fletcher Henderson & His Orchestra playing 'Radio Rhythm':
Jimmie Lunceford & His Orchestra playing 'Frisco Fog':