James,
Sure. The rule of thumb is 10% the total of a component or system. It is not hard and fast. Because while wires have general characteristics and overall with additional cost they sound better… generally lower noise floor, greater dynamics and transparency… they are in your system. Each system is unique and will perform differently in each. The better the system, typically the bigger impact… looking at it as if it is a scientific instrument, the higher quality, the more sensitive. so a percentage makes sense… at least as a starting place.
Also, maybe one component has a very delicate sound and the interconnect is masking it… then it can have a very out sized effect.
Ten percent is only a place to start. I have had interconnects that cost 30% the value of the unit and were worth it, because I could not trade up components and get that sound quality boost. So, they must clearly pay for themselves in terms of sound quality improvements. This is why this tends to be a lifetime pursuit. To get good enough to know the value of sound quality among components and accessories and know your own values is a complex and long termed pursuit.
Buying used can get more impact. The Cable Company offers lots at roughly 1/2 price. Great was to start. I bought older Transparent to verify these were good solution and then bought new and higher level during a system upgrade.