the philips 5r4gys is compatible with the WA6-SE, i didn't like it though, was mediocre sounding on the WA6-SE, i found it to be slightly better on other amps. its an okayish tube, thats about it. the CV 593 is much better
yep they're good tubes, but needs rectifier like 596 to balance that bass out, its a nice synergistic combo, but otherwise, yeah very bassy slightly muddled. i like the 6GL7 but the description on the woo website that says you will hear every note with breathing air around it, definitely not true..
the ts 6f8g are very good tubes, dont think superior to 6sn7 though, also 6f8g have noise problems sometimes and its hard to get good pair but same for 6sn7i do not like the new production tubes though, the treasure cv181 are OK, but NOS 6sn7 still better.i had 596 rectifiers on wa5, but i find the cv593 to be alot better and its only like $150 for a pair or so, was cheaper until only recently
you'll be fine with Sophia 6SN7.... at least this picture seems to show its ok... the tubes touching shouldn't be an issue, though certain areas of the tube might be a little warmer, like small hot spots, but i don't see any real problem, also the woos always seem rather cool, both amp and tube temperatures..