Suggestions for an integrated upgrade please

As rbstehno said, the NHT 3.3's do not work well with all amps. I owned a pair for 7 years and experimented with a few different amps and eventually settled on separates. An Audio Research SP-10 and a Counterpoint NPS 400, both of which had tubes. It was the only way I could listen to the speakers for more than an hour at a time. The tweeter was way too hot otherwise. That was the combination that was demoed to me when I bought them. My Audible Illusions preamp and Aragon amplifier were close but ultimately I decided that I needed something a bit mellower sounding.

I would second Tomic601's recommendation of the Aesthetix Mimas which I currently own. I sold the 3.3's many years ago but since you like them the hybrid Mimas would be a great choice. Good Luck!

I just bought a Technics SU-G700. Superb sonics with a kind of retro vu meters look. It really brought out a lot crisp detail that I had not previously heard. I'm running Zu Audio Omen MK.I with the Technics SU-G700. You may want to read the reviews for yourself. I would not have considered Technics until very recently, but am ecstatic with its performance. 

Ayon Tritons 3

You need big power to drive those speakers Think High current 150 peak current and up.I don’t find those speakers to be bright or to sound hot in the highs......

+1 @panzrwagn

All of his suggestions can also easily be serviced if there is ever an issue

One idea could be a new Benchmark AHB2 + Benchmark DAC3 HGC - form factor would be same size as one integrated amp, and you hit both amplification and DAC in one go - fits your budget & simplifies your chain. I actually would be pretty curious about those

If you are looking at used McIntosh, I’ve worked with the folks at Audio Classics several times and the experience was good

BTW, I run Roon/Tidal off my MacBook Pro - I enjoy it just fine and very convenient

Good luck! Fun decision - let us know what you chose, when the new piece has arrived