Note that the transformer suggested in that thread extracts the maximum power into 8 ohms, and makes it not all that great for lower or more complex impedances. 25V rails (18-0-18 transformer) is about ideal if you intend to drive 4 ohms or your speakers have a complex load.
I recommend a separate higher voltage supply for the tube. 60-75 Volts is good for the 6DJ8/ECC88.
dave