OK- in review, here are the things you need to try:
1) try a different tap (4 ohm)
Notes: the speaker is nominally 8 ohms and likely has a nice impedance bump in the low end that might help your amp out. Any notion that this amp cannot control the woofer is nonsense- this speaker was designed for amps with high output impedance.
I am thinking that the impedance is not the issue here.
2) try reversing the phase of one speaker *only* (not both!).
Notes: If it appears that you have your speakers wired correctly in phase, it may be that your amp has its output out of phase in one channel. In a zero feedback amp, this could happen due to a wiring error as there is no feedback to cause the amp to oscillate (which it certainly would do if it had feedback).
IOW, I suspect phase is the problem.
FWIW, we have customers using that speaker with our M-60 amplifier, which also has a fairly high output impedance and they report impressive results. So you should be able to make this work unless something is outright wrong with the amp.
1) try a different tap (4 ohm)
Notes: the speaker is nominally 8 ohms and likely has a nice impedance bump in the low end that might help your amp out. Any notion that this amp cannot control the woofer is nonsense- this speaker was designed for amps with high output impedance.
I am thinking that the impedance is not the issue here.
2) try reversing the phase of one speaker *only* (not both!).
Notes: If it appears that you have your speakers wired correctly in phase, it may be that your amp has its output out of phase in one channel. In a zero feedback amp, this could happen due to a wiring error as there is no feedback to cause the amp to oscillate (which it certainly would do if it had feedback).
IOW, I suspect phase is the problem.
FWIW, we have customers using that speaker with our M-60 amplifier, which also has a fairly high output impedance and they report impressive results. So you should be able to make this work unless something is outright wrong with the amp.