I had an ARC D115 mk II for four years in the late 1980s and early 90s. It was used to power a pair of Martin Logan CLSes and was preceded by a Beard P101, and then a Spectral DMC10-Delta.
This amp had a very clear and clean midband with that liquid ARC way with soundstaging that is so compelling. It was not particularly defined or extended in the bass, but not unpleasant. It's upper range performance was pleasant, but not particularly extended or powerful. The upper harmonics that allow you to determine what certain instruments are in an orchestra were MIA. Of course, the CLSes are particularly difficult to drive, so I am certain your results would differ from mine. I had no service issues with my unit during the time that I owned it.
This amp had a very clear and clean midband with that liquid ARC way with soundstaging that is so compelling. It was not particularly defined or extended in the bass, but not unpleasant. It's upper range performance was pleasant, but not particularly extended or powerful. The upper harmonics that allow you to determine what certain instruments are in an orchestra were MIA. Of course, the CLSes are particularly difficult to drive, so I am certain your results would differ from mine. I had no service issues with my unit during the time that I owned it.