Proof is in the puddingYou are quite right. There are very many formulae -- do try googling the subject. OTOH, a simple experiment is to use magnet wire (i.e. coated copper wire -- choose awg according to application). Make single core cables for the spkrs first -- you can get away with unshielded. IF you use terminations, make sure yr soldering is top-notch (not talking about using silver/gold/platinum solder; I mean making a good connection). Try these out.
Quite a few parametres affect how the connecting wires (cables) connect (sorry). Load & source impedance is one of these. Accordingly, different wire "recipes" can sound slightly different. But you CAN diy cables & obtain satisfactory results...