Interesting.

While I agree that for a powerful audio amplifier the only good choices are either a state-of-the-art switching amplifier made with gallium nitride transistors or an archaic amplifier with vacuum tubes (while the intermediate historical technologies between these 2 extremes are obsolete), unfortunately it is very difficult to indulge in the latter choice, when the prices of good vacuum tubes have become orders of magnitude greater than in their heyday, e.g. at your link the price for a matched pair of WE300-B is $1500 and for a matched quad $3100, while the price of a complete ready-to-use amplifier is too ridiculously high.