Assuming the interconnect capacitance and preamp output impedance satisfy the constraints I described above, and the speaker cables are of adequate gauge to support the run length (the Transparent Cables site doesn't seem to specify the gauge of the Ultras, though), then there is no unequivocal answer based on technical grounds. And the long speaker cable/short interconnect vs. short speaker cable/long interconnect debate is an age-old one, with divergent opinions (as Stan alluded to).
My instinct in this case, though, would be to go with short speaker cables. Your speakers have an impedance which is quite low at mid-bass frequencies, and which varies widely across the rest of the frequency range. The tube amps will most likely have higher output impedance than your Bryston, and you don't want to have the speaker cables adding to that higher impedance any more than necessary.
If the sum of amplifier output impedance and cable impedance (resistance and inductance) becomes significant relative to the speaker impedance, two things will happen. First, bass damping will suffer. Second, in a situation like this where the speaker impedance fluctuates widely as a function of frequency, then an uneven frequency response will result. That is because the voltage losses across the cable impedance and the amplifier's output impedance will vary as a function of the speaker's impedance vs. frequency characteristic.
Regards,
-- Al
My instinct in this case, though, would be to go with short speaker cables. Your speakers have an impedance which is quite low at mid-bass frequencies, and which varies widely across the rest of the frequency range. The tube amps will most likely have higher output impedance than your Bryston, and you don't want to have the speaker cables adding to that higher impedance any more than necessary.
If the sum of amplifier output impedance and cable impedance (resistance and inductance) becomes significant relative to the speaker impedance, two things will happen. First, bass damping will suffer. Second, in a situation like this where the speaker impedance fluctuates widely as a function of frequency, then an uneven frequency response will result. That is because the voltage losses across the cable impedance and the amplifier's output impedance will vary as a function of the speaker's impedance vs. frequency characteristic.
Regards,
-- Al