An AV Receiver (AVR) is an all in one unit with Processing (HDMI + Dolby/DTS Decoding + Audio processing) and multichanel Amplification in one box. The most common question we get is how can I tune/EQ my 7.1/Atmos setup. 

The short answer is that you can't unfortunately. The chain is such that you have Processing - > Amplification in one box with no way to "add processing" to the chain. The only channel where you could provide processing (and can already reap a lot of benefits) would be for your subwoofer(s). Please check out the following app note for more details on multisubwoofer tuning