I've read speaker cable was the more critical.Because,most amplifiers have low output impedence,and speakers are also low impedence(dynamic impedence as well),so cable length and construction can cause large effect to that relationship.
Versus...
Most sources or preamps have high input impedence(10-50k ohms)and low(75-300ohm)output impedence.So you typically end up with good drive and low impedence into stable high impedence inputs.
Versus...
Most sources or preamps have high input impedence(10-50k ohms)and low(75-300ohm)output impedence.So you typically end up with good drive and low impedence into stable high impedence inputs.