all22s
+1y
the cap should be ran only ro the amplifier. the electrical draw from the radio versus the electrical draw from the amp is like comparing apples to oranges.... a true 1000watt rms amp will pull anywhere from 50-80 amps. but again for the amp to push that much it will need proper power. a capacitor of at least 1 farad (normally use 1 farad per 1000 true watts), an external (second) battery like an optima, decently sized power wire (4 gauge minimum).
if you are worried about your electrical system being drained from your amp (lights dimming at night, dead battery etc) you should add a second battery/capacitor and minimum of 4 ga wiring.
if you are using another amp for mids/highs then also take that draw into consideration as well. the stock mazda alternator only pushes from 50-60amps MAX! a 100amp 1 wire alternator will push around 40-60 at idle and 100amps when running at 2000rpm and above.
also make sure you have a good and dependable main battery as well. also consider using wither a battery isolator or a stinger sr200 relay to charge the back battery while you drive as well as "disconnect" the rear battery when the truck is turned off. that way you wont have to worry about killing your main battery if you play your system with the vehicle turned off.
hope this helps you out.
jeremy