You don't specify which version of the WP you are looking at, but I'm pretty sure from the 5 on they all present a similar load. I have 5.1's and, like Lenny, use the ML 335. I tried a number of tube amps before I settled on the 335. Unless you go with a monster tube amp my experience is you'll do better with solid state. I agree with what was mentioned earlier, a strong suit of the WP is slam, dynamics and speed. The more current your amp will deliver, the better bass control you'll get.
Tubes can sound good with the WP, but in general solid state compliments the strengths of the WP a bit more.
Tubes can sound good with the WP, but in general solid state compliments the strengths of the WP a bit more.