Speaker cable length


Hey y'all,

I'm thinking about changing the setup of my rig so the equipment rack is off to the side and nothing is between the speakers. However, that's going to entail a much longer set of speaker cables. Is there anything about speaker cable length I should be aware of? And and am I right in assuming that I need to keep both pairs of cables equal length?
128x128simao
If your line magnetic 518 is this:  https://www.stereophile.com/content/line-magnetic-audio-lm-518ia-integrated-amplifier-specifications
Than you should not be worried about the cablelength...just keep it with low C. The nature of Tube Amps is of low to very low DF. As so, cable's resistance is insignificant. 
II use Canare 4S11 speaker cable.  Left speaker has an 18 foot cable, right speaker has a 15 foot cable.  Can’t hear any difference.  Won’t set you back more than $200.00 total.  The bested a pair of cables that were $1500.00 each. 
So I did the measurements just now. The right speaker is going to need 18 to 20 ft. The less speaker is going to need maybe 8 ft at most. Because of my triangle ratio with my listening position, a specials are about 11 ft apart and that accounts for the big discrepancy in the speaker cable length if I do move everything off to the side.
If you ever have cause to sell them, a pair of SCs of matching length will be much easier to move.

Also, if you reconfigure again, there's the possibility of halving them to creating bi-wires.

If you're going to purchase long cables, at whatever price point, Blue Jeans, Audio Envy, whatever, I wouldn't save the few bucks by skimping.