Audio Research Classic 30: how does it compare to ARC current power amps?

This may not be of much help, but since no one has chimed in I'll give my thoughts. I used to own a pair of Classic 150s (converted by ARC from M300s).  I assume that the Classic 30, like the 150s, runs in triode and also has a solid state input stage.  I ultimately felt the Classic 150s were too "dry" sonically for me--i.e., the sound was not as rich in the midrange as an all-tube unit, tilted more to the high frequencies.  Having heard the more recent ARC designs, that dryness seems to me to be gone now, so to my taste I'd go for a newer unit.  If I had an old D250 or another of the early ARC units like daveyf I might not want to give up that sound, it is an addictive and classic tube sound.  In your case, you seem to like the CL30 sound, so I'm not sure how you'd like the newer units, which will have more power and bass control but will be more harmonically fleshed out, which might lead you to feel they don't have quite enough detail. I do think, though, that there should be more than enough detail in the newer units to satisfy you, as the ARC house sound is still about high definition.  What speakers are you driving?.