NEED TO REPLACE OLD FAITHFUL- WHICH AMP. SHOUD I CHOOSE

All of those amps you listed are middle of the road. Look into a 30 grand Pilium integrated since I don’t trust whatever preamp you are hooking it up to either since audio research is entry level hifi and the later preamps I heard sounded like kind of bad! It is called the Odysseus. You can hear them in NY. I would also suggest a pair of new speakers since Dali is kind of bright.

YG acoustics Carmel 2 is good and easy to place in a room. Magic A5 also a fine entry level speaker. Another good one is an Amphion Krypton3 that are easy to place in a room like YG. Magico needs a little more room. From what I am reading you need to start over.

Right now my D400 is in the shop, and I am waiting to rear back from them next week. They  said it sounded like output transistors, but said now might be a good time to re-cap too. He was confident that he could get all the parts needed to do the repair. The shop has been in business for over 40 years and I have used them before, and trust them. I will keep everyone posted on what happens.

In the meantime I am still shopping for a new amp. 

I suggest you compare against a Primaluna. My experience in that price range nothing came close. I went integrated because of space. The 30wpc punched better than a 100w Shiit Vidar, got louder with less disortion. Better sound. At the showroom compared against a Hegel H390. I liked the accuracy on the Primaluna how the instuments and details in the sound. How the reed in the Sax vibrated, cymbal ring and decay. Primaluna Bass was not more deep but more defined to hear the strings in the Bass instrument more than the Hegel which was good. KT 77s made it even better.

I’d look closely at the Atma-Sphere Class D. They are simply amazing.