For being a true gentleman, not to mention an excellent amp builder. After chasing my tail for almost a week with a used Cornell Plexi bought from ebay, the problem I was experiencing has been traced to preamp valves. I know they should have been one of the first things checked, but it's a long story, suffice to say it won't happen again. Denis answered his phone everytime and took the time to speak with me, emails are always answered within a day. He also offered to phone and talk a local tech through the amp when it was on the bench, or give it a free ckeck up if I decided to ship the amp to him. Now, he tells me he will select a pair of preamp valves and send them to me for the Plexi. All this considering I bought the amp used and saved 30% off the new price, outstanding customer service. I will buy Cornell again and again after this experience.