I came across this photo of a recording session at the Victor Talking Machine Company. It's apparently from 1910 (I'm seeking confirmation on that presently).
Featured, I presume, are members of the Victor Orchestra doing their thing. But if you look at the far right, next to and behind the tall chair upon which the cellist is sitting, you can see a tuba player. Here's a close-up of that portion of the photo:
Compare that with the photo below, which shows Conrad in a Victor poster that was produced in 1918 for use in schools. It appears to be the exact type of chair that we see being used in the studio. And is it just me, or does that look like the same shoes in the photos as well?!