I hear the same difference. "Depth" and "air" is a good description of the difference between good OTA audio and even a high quality stream. There is something almost liquid or a softness about some OTA FM audio - a very slight reverb or echo - at least the stuff that isn't compressed to hell. Streams are flat. Have you ever listened frequently enough to a station so that its OTA sound was burned into your brain, then walked into the station and heard it on the lobby monitors? Flat. That's the difference I hear between OTA and streams. Still, I am grateful for streams. I'm in Pa., and yesterday I was listening to some old stoner DJ (his description) spinning late 60s psychedelic tunes on KPOV in Bend, Oregon. Obscure stuff I'd never heard before. These are wonderful times we're living in.