New/Used Amp recommendations for about $3k-$4k?

Yes after having the XPR-1’s in my system and going back to my UPA-1’s I want something else. 
I am using a Marantz 8805 preamp. 
I’m not interested in tube amps. 

Well there you go... a monster AV Preamp at the heart of your system and you aren’t satisfied w/ music performance. Let me guess, guitars could sound a bit meatier, brass a little brassier, vocals don’t have that holographic 3d realism, performer in the room with you type of thing. Maybe a few panes of glass could be in the way? If only there was a solution. Enjoy the SS amp merry-go-round.

todd1010 OP
I’m looking some new Paradigm Founder Series 100f speakers and would like to get rid of my Emotiva UPA-1 mono blocks for something else.

The 100F’s drop to 3ohms around 100hz, but!! are also -45 degrees phase angle there too, which means they could be as 1.5ohm EPDR load as seen by the amp.
https://www.soundstagenetwork.com/images/stories/loudspeakermeasurements/paradigm_founder_100f/imped...

https://www.soundstagenetwork.com/images/stories/loudspeakermeasurements/paradigm_founder_100f/elect...

If you want the very best out of them in that bass area, suggest an amp that won’t flinch at those kind of bass loadings.
My suggestion for your budget would be used John Curl’s Parasound Halo JC1 monoblocks. They can be switch to high bias sweet Class-A sound for serious listening. And low bias for other listening, rock or background.
https://www.stereophile.com/solidpoweramps/774/index.html

Cheers George

What I was digging about the 100f’s were the mid range/tweeter.

I'm very curious about those GAN amps mentioned above. 

I’m very curious about those GAN amps mentioned above.

Great if things stay above 3ohms, but your 100f’s don’t, they won’t bring the best out of that bass area like the JC1’s could. 

Cheers George