Q: how much actual load is that putting on your electrical system?
A: I'm putting the load across the battery terminals. I don't plan on loading down any other circuit branches by putting the power amp on any existing circuit. Yes I'm aware of the spider issues.
Now we're having a constructive discussion, and that's cool.
Connecting across the battery terminals does not reduce the load on the stator in any way, shape, or form. Current has to come from somewhere, and the battery can't supply it forever. It has to charge to balance the discharge, and that comes from the stator. You need amps (amperes) for your amps (amplifiers.)
I can't find it now, but somewhere on here (maybe one of the FAQs, I didn't look there!) there's a good post or thread about measuring the load with a voltmeter. Basically, voltage across the battery drops as the bike's accessories soak up the stator output. Guys with aircraft landing lights mounted on their mirrors, and heated gear wrapped around their torsos and limbs will tell you all about how long the bike will [not] run when the volts get down into the low 13s. A stock bike, no added accessories will run about 14.2 volts while riding. Adding auxiliary lights and heated gear are the big loads commonly added, and Gen-I bikes don't take to having both, quickly getting in to the mid-13s with either add-on. Doing both is out of the question. Gen-II has more output, but the harness is still weak in a lot of areas, apparently built with "They won't really do all
that" in the back of the engineer's mind.
If you do this, keep a voltmeter across the battery, and watch it as you crank the system. If you get into the low to mid 13s you're running on battery resources, not alternator output, and the voltage will keep dropping until the ignition stops, or you turn off the music.
If it stays in the high 13s then you're golden.
Just for an example, I added loud horns from Discount Auto Parts to my bike, they mount in the same place as the stock horns, no clearance issues, but they draw a huge load electrically. I run 'em through a relay to keep the horn button from sizzling. Hitting the horn at highway speed (meaning maximum or near maximum stator output) drops my volts from 14.2 to 13.3 or 13.4. Just honking the damn horn, nearly a full volt! If I had heated gear or big-*** lights, the bike might shut off if I honked the horn! :huh:
As far as speakers on the bike, I think you'd be making a
huge effort to cobble something together that will sound marginally better than something you recorded on a portable cassette recorder by holding its mike to a phone that was playing music the guy in Germany was playing when he called you (speaking of polkas.) The
only advantage it would have is that it could be shared, whether those around you wanted it shared or not.
Earbuds or good helmet speakers (like something stolen out of a good set of headphones) will blow away a speaker set any time, any place.