Separate Amp for AV receiver

I have a Denon Receiver, AVXR4300H. Not happy with it. I'm considering an inexpensive 7.2 channel amp to see if it will help. Does anyone have a recommendation.
I have a great HT system, built around a high end Meridian surround processor, and a massive Rotel 5 channel amp, and B&W 805 speakers and subs. While it isn’t in serious competition with my two channel system, it sounds great. The same principles apply to choosing all the components for the Home Theater as two channel. Except I feel because of the distraction of the video, you don’t have to go quite as far along the SQ path.
OP, you have a nice 2 channel system, but you can’t compare your mid Fi HT components to premium priced 2 channel equipment and make a valid comparison.  It’s like expecting the same performance from a Hyundai Sonata and an upscale Mercedes Benz.  Since you like McIntosh why not get a receiver or Pre/Pro from that company and then make a comparison?
Stereo (2-channel) is stereo, HT is HT, and never the twain shall meet.....I have three HT systems, two based on separates, one with an AVR. They are hardly ever used for music listening, maybe FM once in a while. I will have to admit that AIX discs in multi-channel format can sound pretty goodon a higher-level HT set-up, and all concert DVDs/Blu-Rays benefit from the format also. The trick there is that video is part of the mix on those discs, soit's akin to watching a movie (ever notice how music sound-tracks in movies usually sound pretty damn good?). The eye-candy enhances the audio portion and vice-versa.
Ok, lets take a look at ur HT speakers, what are you using ? Do you have subwoofer(s).
does the system lack slam ? If its HT ya gotta have slam, slam is where the money is Lol. Sounds like you have a nice 2ch system
Lets look a little closer at what its NOT doing for you, HT seems pretty straight forward, hook up all the speakers and bam its a HT, not always…..