Thanks, Bill. (I take it ToneDeaf Dave wrote the parody lyrics, right?)

Here's the video of the French Horn and Uke duet:

Fred Sailer and Dottie Hurley: Mozart Horn Concerto No. 3, Second Movement

I think the sound came out pretty good on that one. That's partly because the French horn is a pretty loud instrument and the mic picked up a its sound directly.

Again, it illustrates how the variations in sound quality are not all due to the recording equipment and its quirks. There are many factors.