Does anyone on this Forum have any experience with Audio research ref 610t monoblocks

Good afternoon. 
I have a chance to pick up a set of very nice Audio research ref 610t monoblocks . I believe there rated at 600 wpc, class A, or A/B, not sure. I think they use around 16-20 tubes. It’s a older amp, older technology. But in the 70s they sold for around 40k for the set. Anyways, I wanted to know if anyone here on the board has a pair, has heard them, and get your honest opinion. How do they sound? Are they noisy? 
How would you compare them say to a Prima Luna,, etc, etc. I know they are super heavy, I think 170 pounds each . And the tubes can be expensive. But I’m trying to find some people that can tell me there experience with these amps. Thank you


If this is still alive, I'd have the amp checked by a competent tech, what's the retube cost and how stable is this amp-- I've owned a fair number of early ARC amps and a few preamps and other components. If the amp checks out, doesn't kill tubes and tube replacement is reasonable, the price should be Not Crazy. 

I was more partial to the lower power -- 75 watt- range of ARC but that was many decades ago, when Bill Johnson was alive. Modern ARC can be good. But know what you are buying. 

Very impressive amps! I’d be tempted as well. They are almost 20 years old and are likely on need of service. Does the original owner have any maintenance records from ARC or one of their authorized repair centers? In my experience ARC amps have large capacitors that need to be replaced at around 20 years. I had a D-115 that weighed around 85lbs and shipping it off for service was a bit of an event. It looks like these amps when boxed are 200lbs each. Does the current owner still have the original shipping boxes or crates? Can they be re-used for shipping?

Also, the previous advice to pair with an ARC pre-amp is on point. I like the LS 28SE and of course the Ref 5SE and Ref 6SE are highly thought of.

If that doesn’t dissuade you then you should absolutely go for it!