long run speaker cables for mcintosh mc602

Could use some help finding cables for a mcintosh 602 amp running proac 3.8 loudspeakers. Prefer them to be single biwire. Looking at audioquest slate... Any owners have an suggestions, need to keep price around 300 for a 12-15ft biwire pair, dont mind used. Thanks
Try SignalCable.

I use their Ultra cables for my MC501s. They have bi-wire versions of this model as well.