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No need to buy a new compatible receiver. Just buy a $20 splitter and that should get the job done. You could put off that upgrade a few more years.

On the published specs for the Apple TV for "Audio Formats" it lists:

HE-AAC (V1), AAC (16 to 320 Kbps), protected AAC (from iTunes Store), MP3 (16 to 320 Kbps), MP3 VBR, Audible (formats 2, 3, and 4), Apple Lossless, AIFF, and WAV; Dolby Digital 5.1 and Dolby Digital Plus 7.1

So I guess we're assuming that the Apple TV will have a setting that will let you switch the audio output to either Dolby Digital 5.1 or Dolby Digital Plus 7.1? From what I understand those cheap splitters can't send Dolby Digital Plus over optical audio out.
 
I have my ATV (2nd gen) HDMI out to my 7.1 receiver for home theater and it's Toslink out to Zone 2 on the same receiver so I can play iTunes and/or Pandora (via Airplay) outside on my deck speakers. My 7 year old Denon receiver only outputs analog to Zone 2 so I have to use a little converter box. So with only HDMI in the new ATV it looks like I'll have to find one of those switchers others have posted or buy a newer receiver that supports digital out to zone 2. Haven't totally thought it through yet but would like to see if anyone else in the same predicament. I definitely want to pick up the new one. I recently jailbroke my ATV and played around with some of what I can do with it but wasn't terribly impressed. So, may be resetting it, putting it in another room where it probably won't see much use, or selling it.

I have the identical setup. I just put an Airport Express on the Zone 2 input and set up the Apple TV for video only. I posted above, you can get the old G-Band AE's on eBay for less than the switcher boxes. Snag one and hook it up to your analog input and hide it behind your receiver. They are going for less than 30 bucks.
 
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