Didn't say I was at the maximum but that I was near full volume and have no headroom really.
I will be adding a power amp and if it doesn't achieve what I want I will sell it.
But this is not the advice I'm getting elsewhere also.
Doesn't really make sense, it is common and others do it wilth a similar setup, i'm doing doing anything odd. There is about 50 - 60w getting to my speakers which can handle much more and I have no headroom. With a power amp, I will get more volume, headroom and less stress on my Denon which gets quite hot so I have a fan on top of it to cool it automatically.
I just googled the Denon 4500H manual for the details. It says
"…the power amplifier provides identical quality for all 9-channels (165 Watts x 9-channels)"
The difference between 165 and 200 watts could be noticed on speakers capable of handling them. But it would be very small indeed. Most of the heavy lifting, and a huge draw on power is in the 20 - 150 Hz range, the large part if that is the two subs. You don't mention the volume of the space you listen in, which would dramatically affect your perception of loudness. With high sens speakers like your Klipsch, your amp is plenty powerful for a medium-large room, maybe 12 x 18 with 8 ft ceiling.
I have the Denon 4400H in a 5.2.4 Atmos setup. I did try a 7.2.4 setup and went down to my current setup because the additional rear surrounds didn't add much for me, nor friends I asked to help me A/B the differences.
You don't mention the crossover settings for the subs, but being an SVS 2000 owner, I can't imagine that those subs don't blow you out of the room even set at the initial 12 noon setting on the sub amps.
I used to think of the watts handling of speakers needed to be matched with the amp. It is important to be in range. But it doesn't have to match. Think of the Watts as the upper limit before the speakers blow out. Or the amp will send blow a fuse. The sensitivity range is more useful in home theater settings.
A very sensitive speaker for a center channel (70% of a movie's sound energy) and very INsensitive surrounds (requires more power from the amps to match center speaker general level) would give that Denon amp a hard life.
But to answer what amp? I'd upgrade the Denon to flagship level. Or a big Emotiva. When using Audyssey or Dirac or REW for timing and phase corrections, trying to spread that between four or five amps is honestly a challenge.
And it is more critical to do with separate power amps. Dolby Atmos and other 3D audio codecs, need very precise timing— so sounds simultaneously arrive at the listener seat. That is important for the helicopter's overhead flight path to be "believed" by your brain. (The aliens walking "upstairs" in A Quiet Place? It still makes me want to check my attic!)
Here is the amp manual:
Denon manual for X4500H