FWIW, I also had a Yamaha CR-620, the double-sized cousin of the 420 (40WPC@8Ω). It worked just fine, and had been checked over for the typical Yamaha poor solder joints as well as having some new caps in the audio path. I still have the "little" Kenwood and gave away the Yammie to someone having a garage sale, just to get rid of it, with the instructions that if it didn't sell I didn't want it back. I also advised that the seller not keep it unless she really wanted to be underwhelmed.
It's not that I have any kind of super-critical aural acuity or special tone sensitivity, but simply that I didn't like the sound compared to the 20+ Pioneers and Kenwoods in my racks. Your results may vary.