Audio Research Ref 110 break in period

I found the break-in period to be fairly uneventful, meaning no wild fluctuations. At the outset the amp was congested, and frequency extremes were a bit limited. The high end extension came in at 300 hours, and the bass began to settle at 400 hours. Beyond 400 hours you will start to get a refinement of sound with the midrange filling in rather nicely. Keep an eye on bias adjustment at 600 hours.

To be honest, I was a little worried in the early listening stage, put patience was rewarded, it is a great amp, especially with the kt 120's.s

I've never heard of an ARC amp that does not have the teflons take 600hrs. to break in. I would say a maximum of 1-200 hrs. should be sufficient. That being said, if it does change after that period would love to hear about your confirming what Ff116 found. I'm wondering if it's the KT-120's that's taking the increased break in period?

the sound will go down below the line at 100h+ but it'll get better at 200h+ i don't mean that it will go that bad but a bit unstable.
at least that's what happened with my REF150

Nice amp! Thank you for the feedback.

Did you upgrade from a Ref 110? If so, I would love to hear the improvements you have found over the Ref 110. So far with my Ref 110, I cannot imagine a better tube amplifier, but I know the huge increase in power supply caps and new teflon output coupling caps have to make a very nice upgrade on the Ref 150. I am going to have my LS17 preamp upgraded to the new SE version by ARC in a couple of weeks and am looking forward to hearing the new Teflon caps... According to ARC there are deeper, richer tonal shadings and even less "grain" overall - not that I have been able to detect any apparent grain now. Guilding the lilly...