Suggestions for an integrated upgrade please

You can get a Naim Supernait 2 or 3 in that price range. If you want something new, the new Lyngdorf 1120 is an amazing piece of kit. It is extremely impressive and has built in room correction. At $2500, I think it is one of the better hifi values currently going.

At one point, I had a BAT VK3000.  I was a wonderful integrated and had a great soundstage and a magic to the sound that made it easy to listen to for hours.  I changed speakers and had to move to something with a bit more power otherwise I would still have it today.  You can probably find one for around $4K used.  

A lot of good information here... BUT... unless you’ve (or they’ve) listened to the same set up with various amps you (they) really can’t conclude much.

I would have no idea what electronics (i.e. source, preamp, amp, etc.) would sound good to you, since I’ve never heard a set up like yours with various electronics - nor, do I know what sounds good to you. That would be true of anyone else posting a suggestion.

However, I can attest to the quality of the sound of Harbeths driven by Hegel electronics - since I have that set up. And... as Alan Shaw suggests... his speakers do, quite litterally, sound best with Hegel electronics. Because I have several Harbeths and I’ve listened to them with various amps - both tube and solid state - I can make this statement - but - only in the context of what sound qualities I prefer.

And... that is the point... you will never be able to adopt all (or any) of the good suggestions in this thread... and... necessarily, achieve the sound you seek... except by mere chance!

So - you should start by contacting the mfr of your speakers and inquire what electronics they use to demo their speakers, as well as seek the experiences of others with your speakers. There is no other way - except - "chance."

I second the Naim Supernait 3. Pleanty of power, drive your speakers (PRaT)

Try the Canor intergrated units . The hybrid unit well made and acurrate unit .

The vinnie rossi l2 is a great integrated

Maybe a used Krell K-300i?  Lots of power, class A sound, lots of very favorable reviews, and is not bright.  Not sure if it can tame the OP hot sounding tweeter.

Interesting review of this amp on the ASR website! This is a 15 watt amp!😄

As someone who owned the NHT 2.9 with Bryston gear (what was I thinking). I can recommend the KRELL K-300i which I own now. I use the KRELL with an equally bright headphones as the NHT and the KRELL tames that beast nicely. I would expect the NHT to work nicely with the K-300i.