If one set is no more than 50% longer or shorter than the other, it would be a miracle if you could reliably and repeatedly perceive a difference. If you want to try it out, cut some cheap 12 awg lamp cord to your desired lengths and try it for yourself before you use better cables.
Cable length question
Speaker cables bi-amped
One cable from amp to main mid and upper frequency speakers.
One cable from amp to sub woofer high level input, another cable from high level out to the bass speaker on the main.
Stereo subwoofers so this arrangement repeats.
Question 1 should all cable be same length? Or
Question 2 should all lengths be equal? Meaning the mid and high frequency cable length equal to the sum of the amp-sub-bass main length?