i actually find my k702 pairs better with my caliente than wa6.
with the wa6, i rolled 6 or 7 different types of tubes, and nothing did it for me.
my general impression with the wa6 is that it brought the mids forward just a shade, and sweetened and rounded off the bass just a shade.
so the k702, already being bass shy and upper-mid strong, didn't sound great to my ears with the woo.
i will say the treble sounded fantastic on the woo, though...
but, we all have different preferences in sound signature, that's one of the reasons this forum is so much fun...