OK, a possible formula given a digital system:
Source - 20 to 25%
Amplification - 25 to 35%
Speakers - 25 to 45%
Cables - 10 - 15%
Summation of the mid value of each components class = 100%
Source - 20 to 25%
Amplification - 25 to 35%
Speakers - 25 to 45%
Cables - 10 - 15%
Summation of the mid value of each components class = 100%