(the Apple TV doesn't go thru the TiVo I don't have a Bose system though)
also see this re lack of sound can be a problem with Apple TV
If you hear static or if you don't hear any sound on your Apple TV
Adjust your audio settings and check the audio after each step: On your Apple TV, select Settings > Audio & Video. Make sure Audio Out is set to Apple TV. Change the Audio Mode from Auto to 16 bit. On Apple TV (2nd or 3rd generation), change the Dolby Digital Out setting from On to Off. If there's no sound when you navigate the menu, choose Settings > Audio & Video and make sure that Sound Effects and Music is on.