I think it comes down to how much you want to spend, I'm sure the Appollo is a great sounding preamp and I considered it for my system but went with a TVC instead, mostly for the reason to stay off the grid. For around $1500 you could put together a killer sounding system with a Ref. 4 TVC and the EL34 mono's, you could upgrade the transformers to C Core or Double C Core for a bit more.
I run a Ref. 4 TVC and the 2A3 monoblocks on my 99db speakers and the combination sounds wonderful, I've been considering to upgrade the transformers on the 2A3 amps to double C core but the amps sound so good bone stock that I'm not sure the upgraded transformers would make that much of a difference.
You can't go wrong with Promitheus gear and I do believe having all the components from the same manufacturer will give the best synergy, just decide on your budget and go for it, and be patient while waiting for it to be built.
Greg