for horns: a networked-type speaker cable has worked out very well for me: MIT paired with classic Belle Klipsch.
Regarding conversion to biwire: although my MH750 Magnum's are biwire, I wouldn't necessarily expect a significant improvement in going from single to biwire with the same model of cable. Sometimes a switch to biwire is better, sometimes indifferent, sometimes even a degradation; you just have to try it.
So in this situation I guess I'd probably try some different interconnects, although not knowing about your equipment or present cabling leaves significant info. unknown (in terms of offering a worthwhile opinion).
Regarding conversion to biwire: although my MH750 Magnum's are biwire, I wouldn't necessarily expect a significant improvement in going from single to biwire with the same model of cable. Sometimes a switch to biwire is better, sometimes indifferent, sometimes even a degradation; you just have to try it.
So in this situation I guess I'd probably try some different interconnects, although not knowing about your equipment or present cabling leaves significant info. unknown (in terms of offering a worthwhile opinion).