The amp I’m building is VERY similar to yours – 417A driver, cap coupled (Jupiter beeswax), all James iron, Blackgate and Elna Cerafine caps, Mills, Riken, Tantalum and Caddock resistors, WE copper wire and Cardas unplated copper binding posts. All tubes will have AC heat but I’ll use humpots on the 45’s as I hear this adds more flexibility for tube swapping. The chassis will be punched stainless steel and SA Mahogany, similar to my first DIY 300B SET. So far I’ve rounded up Western and Northern Electric 417A, Raytheon 5842 and ST 45, RCA UX245 and a few NOS 5U4G and GT rectifier tubes to try. I’ve added Riken shunted ALPS blue velvet level pots for each channel so I can use these to attenuate the 604 horns when trying passive line-level crossovers. I’ll post a picture when I get a little further along on assembly.

Bill