I know I'm chiming in on a 3 month old thread. I assume RayRay8 has his amp and all is well, but for what its worth. I've built with the same woofer on the Fritz Grove. It is also the same driver used in the Totem Forest. It does not have any crazy impedance dips, and the real question is phase angles. This woofer does occasionally go reactive in phase angles, but overall is a capacitive load. MOST, not all tube amps will drive this speaker fine as long as you have enough power. Also RayRay8, This woofer really takes along time to break in, I would recommend to not take anything that you hear to heart until you have 200 hours on them. They will still get better up to 300 hours, but at 200, you'll have a good idea.
Good Listening, Tim
Good Listening, Tim