@leahy a friend bought one of my former fully upgraded Cary strapped triode/ultralinear amps (el34s), and right afterwards he sent his other CJ tube mono amps (6550s) and CJ mosfet ss amp out for full upgrades; selected a real expert master level tech. Upgraded all caps, resistors, diodes, and more - same as the Cary units had. He just had to know if upgrades really made a difference in the units. Both the Cary units and CJ units were brought to an entirely different level.
In all cases the fully upgraded preamps and amps won over one brand vs. the other. Another consideration path for your CJ45 if its not already upgraded. I'm a Cary owner myself, if you go 300B Cary's plan on higher sensitivy higher impedence speakers too in order to get the most out of the amps and pricey 300b tubes, fwiw. Other fleawatt owners may chime in for other references if you go this route.