Shouldn't it be crisper/cleaner/more vibrant?

I'm not familiar with your amp, but I have owned Cornwall IVs and they are very capable of what are looking for. As @hilde45 mentions, your room might be the issue. Also I would question whether a streamer/amp combo would give you the best results. The Cornwalls love a tube amp and ultimately, that's where you should be IMHO.

It should certainly be crisp and clean with Klipsch. Not sure that you will get vibrant out of an all in one Class D setup. I don’t want to go too far down the cable rabbit hole, but what are you using for speaker cables?

My guess on cause would be bass muddying the rest due to room acoustics, which is a most common occurrence with many rooms at home.  
 

Try isolating speakers from floor better and and adjusting location if possible.

Applying room correction//DSP/eq would be next.   
 

You want crisper, cleaner, more vibrant?  Play more records!  ;-)

I agree, not the best model if you favor brilliance (or require due to your hearing).

I also suspect you have the speakers too close to corners or either rear or side walls, the excess bass that creates clouding the mids and highs.

If it’s WAF (wife acceptance factor), then you need mobility, 3 wheels that resist, but allow movement: push them back when not listening, pull those beasts out when it’s time for them to sound great. That gives you the option of trying different toe-ins, including for one centered listener or two off-center listeners.

https://www.audiogon.com/systems/11516

I roll mine into the corners when we have a large group for dinner. Of course, mine is a living space, requiring flexibility, not a dedicated man-cave.

There’s nothing wrong with using a good equalizer to get the sound to your liking.