You can always go for Carbon as the reference. It made the difference between 009 and 95x a lot smaller for me. You can use the power supply for Carbon with the GG which has tube output devices(similar to BH), so you can have two amps with different flavors for the total cost of a little bit more than for only Carbon, or only GG. This is what i have done in my system.
I have also built SRX which pairs nicely with 009, but Carbon/GG are my favorites.
https://www.thedrive.com/the-war-zone/44697/ukrainian-tu-141-strizh-missile-like-drone-appears-to-have-crashed-in-croatia?xid=fbshare&fbclid=IwAR3hBI9aVjRTVCFuHBreFsNANSSttDtEcroAhCq75KpFOBT9WcGBwg3aej4
something from the close neighbourhood.
Installed 2sk170/2sj74 instead of THAT340 in my SSDynalo. Did not listen to it for a long time, but initial impression is that HD800s feel less fatiguing. Like it had just enough cups of coffee, not one or two to many.
I saw three different gerber files. 1 with trough-hole, 2 with smd components. The one i was looking at was "diffinput6a" - with smd components.
I saw your project also, with trough-hole components, so that is also an option.