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.