Need to learn about Audio Research

Audio Research (AR) was really the main brand to originally be used for Demo's of the Magneplaner's. AR and Magnepan had a collaboration when they first started selling their speakers. I remember going to audio shops back in the 70's and those 2 brands were always together and sounded magnificent. I think AR is an excellent brand but not necessarily the best value for the money as they are very expensive. You can still get excellent sound with other brands for your 3.7i much cheaper. 

ARC in the 1970’s was at that time relatively reasonably priced. In ’73 the SP-3 pre-amp was $595, the D-75 $995, the D-51 $695.

It was when the Mark Levinson brand appeared that the price wars started, as well as "all out" assaults on advancing the state-of-the art, such as the SP-10 pre-amp, and D-150 and then D-79 power amps.

For a long time ARC had both somewhat modestly-priced entry level products (LS pre-amps. I paid $2995 for an LS-2B in the 90’s) and premium models (the Reference line) with premium prices. Now even the LS pre-amps carry a hefty price tag.

I still have a LS25 mk1 made in 1998 from what I see , it's still rocking 😎 

Got all new capacitors about 4 years ago, and voltage regulators . Great preamp!

Agree that tube pre + SS amp is a good “warm” direction to go from the Hegel H390.

A GanFet amp, which is similar to a warm sounding SS, may be a good option.

Krell K-300i integrated has “150Wpc into 8 ohms and 300Wpc into 4 ohms, with its iBias technology allowing the amp to deliver up to the first 90W in class-A (warmth) —"without the excessive heat and power consumption of traditional Class-A designs,- (Stereophile)

I have used ARC AMPVT150 mono with LS5 preamp since1996, sweet amps to replace McIntosh tube amp/preamp. , there was no mechanical or electrical failure.

My current amps are 160M,without repair last 4 years.

AR is coming out with  some NEW AMPs/preamps SS/Tubes in 10 K range starting in April 2025.