Hello varadas...
You state that you already have a multi-channel power amp, but don't say how many channels and output.
If you are interested in Dolby Atmos (or immersive audio in general), I would suggest that you reconsider your position of not wanting an AVR.
The biggest advantage (and potential cost savings) that I see is that if you don't already have 11 channels of amplification, adding a receiver like the Marantz SR7011 (or its Denon sibling) would give you 11.2 channels of audio processing plus the added bonus of 9 channels of internal amplification that can be used where needed.
For example, if you already own a 5 channel power amp, you can use it to drive your floor channels and use the internal amps of the AVR to drive your 4 overhead spkrs to achieve a 5.1.4 Atmos setup. If you have a 7 channel amp, you can do the same to achieve a full 7.1.4 setup.
Or… you could sell your current multi-channel amp, buy a brand new high power 2 channel amp to drive only your L/R "stereo" channels while using your 9 internal amps to drive your remaining HT channels.
Many people use AVRs as processors only and achieve excellent results... the Denon and Marantz offerings have excellent preamplifier output stages and will supply more than enough "unclipped" voltage to drive virtually any outboard power amplifier to its fullest potential.
See if this would be a feasible option for you.
Good luck with whatever you decide...
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