Mac iTunes (12.4.3.1) playback dropping out on audio Airplay

I have a frustrating problem here that has defied resolution.

I'm running OSX El Capitan (10.11.6) with iTunes 12.4.3.1. I'm playing music from my collection over native Airplay to an Airplay-enabled Denon AVR X-4000. Every 2-5 minutes during playback, the audio drops completely for about 2-3 seconds, although playback continues in the iTunes player. I believe the problem is specific to something in my user profile on the Mac for the following reasons

• I don't get playback skipping using Airplay from any other device to the AVR
• I don't get playback skipping using iTunes Airplay from another account on the same iMac
• I don't get playback skipping using Spotify or other audio apps from my user profile on the same Mac
• iTunes playback continues to skip if I use Airplay to other Airplay enabled speakers in the house

I have tried deleting the iTunes plist and iTunes folder, and I have even deleted the entire application (using Terminal) and reinstalled it. Yet I continue to have this problem.

Apple Support suggested I reinstall the entire El Capitan OS, which frankly seemed like overkill and likely to create other problems. Does anyone have a suggestion about what I can try next?