I have not heard the CA-770.
I am, however, a more than satisfied American owner of a couple of Canary amps, namely, the CA-301MKII, sold to me by Bill Feil whose Audiogon moniker is Audiofeil, as well as CA-339's, which I currently own (sold the CA-301 to upgrade and get more power from the CA-339's). The amps are built incredibly well and sound phenomenal.
I recommend them highly. I am sure Mr. Feil has told you of their less than reliable customer service wjhen you privately emailed him. He used to be a dealer for them and did not have a good experience with them. I don't blame him for not being happy with how they run their company. However, any time I have had a question or needed service I have, with a little bit of effort, been able to speak with them and get exactly what I needed. If you can pick up the CA-770 for a good price, I would not hesitate to buy it. I think you would be very very impressed by its build and sound quality if the amps that I own (owned) are any judge.