a good electrical for any high output stereo starts with the alt and grounds. improve your grounds and get a nice sized alt ( as big as you can that is known to do good not ebay junk). then improving the power wire from alt to batt and batt to amp. if your pulling more then your alt can put out then your dropping down to battery voltage (12.6-12.7). add in enough high grade caps ( not cheap junk) and the caps will charge at the highest available voltage (alt, 14.4-14.8). the amp will then draw from the highest voltage with the least resistance. meaning the cap ( 18" or less from the amp). then the alt and then the batts. a good stout electrical wont drop below 13v, but adding in some caps could gain about 1v if done right. meaning more power to the amps from a closer source.
before I left ak I had a 1500.1bdcp, stock alt, simple interstate batt under the hood, interstate rv batt for extra storage, big 3, and a 10 farad Rockford cap. with out the cap installed my voltage was dropping to about 11volts ( song dependent ). music sounded good bass was deep. installed the cap and I wouldn't drop below 12 volts and the music was louder, cleaner and sounded deeper. the amp was getting a higher voltage and so was performing better. I also had a 250 amp alt that I installed and wouldn't drop below 13volts and that too gave me the same increase that the the added cap did.
conclusion, the higher the voltage you give your amp the better it performs. caps and alt sit at a higher voltage then batts, that is the benefit. it can cost more and if not done right will only be putting a band aid on the issue yes. but correctly done and will see a gain.
hn155: Rockford punch pro speakers, t400.4 deh 80prs, full audio build to come. working towards 175hp n/a, simple but fun.