Hi,
That's a great set up, I dunno if have said the same thing in another of your threads, but coming to the point, the AV QR series are beauties that are fairly easy to drive. The LRs, if I am not wrong, are 90 db claimed sensitivity, and the other channels are not very far behind, if I have it right.
So, the first thing to understand is why you feel the need for additional power? Is there a specific deficit you are feeling?
The SR60xx series are proper beefcakes when it comes to amplification. There shouldn't be a need for extra amplification for your requirements.
What is your room size and how far back do you sit?
The Emotivas have been used by many here and elsewhere, and they do deliver what they promise from my reading.
I have a specific personal grouse against Emotiva in India - they are a low-cost internet direct brand in the US, and the arrival price in India via dealer is just not worth it. If you can source one via a visitor, nothing like it, that is if you are set on adding a PA to your system.
Having said that, short, straight answer to your question will be to DM FM
@ankitbhargava. He runs an SR6xxx powered by Emotivas. And he is one very happy cat.
As I said, your speakers are great. So, I really don't know what you are lacking.
Sharing room size and listening distance will help.
All said, I would suggest investing a small amount in a local PA for your requirement and see how it sounds to your ears.
If you are going 5-channel, go direct to the Emotivas.
All the best