Here is the question from my client:

"Is there a way to listen to music from my iphone and watch a slide show through apple TV at the same time?"

I am assuming he is wanting to do a slideshow using the iCloud slideshow function in the Apple TV, and use Airplay to send audio from his iPhone to the Apple TV while the slideshow is playing. Seems like it should be possible, but you never know with Apple.

I know he can create an iMovie slide show and put a playlist with it. It will all play from the cloud instead of trying to airplay it. Or I think if you go to music on the ATV and start music, then go to the photos app on the ATV, you can start a slideshow of your iCloud photos.

Or you can make the screen saver play your own photos from the iCloud and that would work too

+1

Make sure your photos are PG13. Lesson learned.

If you're trying to Airplay music, the screensaver (which is going to show the slideshow) doesn't activate.   I tested it for you.

Now, if he plays music directly from the iTunes app or another app (i.e- Pandora) on  the AppleTV, it WILL go to screensaver...all he needs to do is go into Settings->General->Screensaver and change it to his photos or whatever he wants to see.

He may also want to change the amount of time (lowest is 2 minutes) before the screen goes to screensaver.  Which he can do in the same area of the settings.