How does cable length affect sound?

I hope I’m in the right forum.  I have a listening room 18’ X 22’.  My speakers with monoblock amps will be on the 18’ wall.  I would rather have my preamp, transport, dac, etc., on the 22’ wall close to my seating area rather than between my speakers/amp. I have dedicated 20 amp outlets on long wall but will need, at the minimum, 11’ power cables to make the connection to the outlets.  I will need approximately 18’(?) of interconnect (preferably balanced) from the preamp to power amps (running along perimeter of room).  Will these lengths of interconnect or cable degrade the sound or is there any specific quality I need to be aware of when purchasing them (if they make them that long)?  Also, should the power cables be of equal length or can they be of different lengths? 
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Thanks all! I want to replace all standard power cables with upgrades. Price is a consideration and I’m new to this. Are power cables analog or digital? I have PS Audio Directstream Jr DAC and  Perfectwave transport, Audio Research AR17 pre, and Krell MDA-300 monoblock power.  Will one brand suit all or are there quirks about each that require individual considerations? I already have BetterCable XLR interconnects on all but the 18’ run I will need for pre to power amps. 
If its not to long you will be ok look at Purist it has great sound and the capacitance is great as well.Keep cables the same length thats power cables.Good luck enjoy!!
Don’t waste your money on power "conditioners". There is NOTHING wrong with the AC from your outlets!
I don‘t recall the OP stating or asking anything about power conditioners. Why post off topic clickbait when it is totally uncalled for?