I have a 272/300 DR that I use for music. I want to add AV for movies/surround by adding a receiver that can handle 4K. But, I want to to main channels to continue be driven by the 272/300. For movies, the AV receiver would do the decoding and pass the two main channels to the 272/300. How do I do that? I don't want to have two separate set of speakers driven separated systems. I want to integrate as transparently as possible.
You need to buy a AV receiver which has pre-outs for the front two channels. The base level models don't but from mid-range Uk they do. Then run a pair of RCA cables from the pre-out to one of the analogue inputs of the 272; for that input set it to "AV Fixed Volume" (within the Setup / Inputs menu).
Now balance the channel volumes / set distance delays (or run auto setup) as normal. The front channels will be amplified by your Naim the rest amplified by the AV Receiver.