Audio Research GS150 vs REF150 SE

Hi Lostbear.
I did have a CL60 for a few months before trading it in for the CL120’s in 1990. The inputs were balanced as part of the mods GNSC performed in 2005. Since 1990 I have several different preamps, phono amps, DACs, you name it, but held on to the CL120’s. Those are very special sounding amps, particularly with the Gnsc mods.
I would likely have to audition a REF150 SE in my system/room so that I can make a sound (no pun intended) decision.
So buying used,without a possibility to audition before a potential purchase is not possible.

Good point about selling my Classic 120’s prior to auditioning a 150SE in my room with my speakers as I wouldn’t want to put myself in your situation with your V70. 

A friend of mine had purchased a V70 used and he did not like the sound in his room with his speakers so it went in the closet for 15 years until he decided to part with it. He listed it on Canuck Audiomart and it sold within a couple of hours of being listed. 

You seldom see a Classic 30, 60, or 120’s for sale on agon. I haven’t seen a pair of 120’s listed here in recent years anyway. The V series is actually the Classic series with balanced input and was not in production for very long before being discontinued. 

Speaking with Chris Osanna at ARC a few years ago about using KT120 in the 120’s (which he did not recommend) he was telling me that they rarely see any of the Classic series amps coming through their repair shop other than for tubes and filter caps replacement. 
He said that those were probably the most reliable pieces (built like tanks) in their amp line. I can certainly vouch for that with the experience I have had with mine.