I have also investigated this and have found the same BUT, not only do you need an adapter, the Avant will not accept the sound inputs so you need an alternative output such as a surround sound system or possibly a B&O music system to plug into other wise you will not hear anything from iTunes. So brand new apple tv in box if anyone wants to buy one and has a suitable system. I was so disapointed, I was sure there would be a way around this with all the brains out there but hey, maybe an excuse to buy a new tv, if only I did not love my Avant so much.
Peter