If you are contemplating a new direction, you might give bottlehead amps some consideration. I far prefer(ed) my crack (with my hd650's and all the more so with my hd800s) to my prior woo 3. (And for reference, I lived with both under the same roof for over a year, generally running Amperex pq 7308s and a 5998 in my woo.) With the ccs boards (speedball) and film caps in place, the crack is a more sophisticated design than a wa3 or wa2. To my ears, it sounds noticeably faster, more detailed and more dynamic (all in all, more involving and exciting) than the woos.
Stepping up to a higher rung, I recently completed my mainline, which is just brilliant with hd800s. While retaining what I think of as Bottlehead's house sound, the mainline has the sort of clean transients, natural timbre, tight impactful bass and accurate but never strident trebles that set great tube amps apart from those that are just good. Topology is very similar to an ecp l-2 (highly regulated, ccs, single gain stage, 6c45pi driven, parafeed tube amp with high quality custom output transformers). Sadly, despite rave reviews (eg innerfidelity), the l-2 isn't presently being produced, but if you are willing to undertake the build, or to engage a builder, mainline is an awesome option.