Wow - that is bizarre R3Tex - I was already in middle of reply when alert came up and saw you had tagged me!
... Looking for info on installing Cycle Sounds 3 speakers on a roadster.
Is this what you have?
http://www.cyclesounds.com/series-3-premium-amplified-speaker-kit-universal-metric.html
What are you using for the music source?
... There's a constant loud noise when hooked up through headlights and there's no kill switch to turn the speakers off so I don't trust leaving them hooked up directly to the battery. ...
If you have connected to the headlight, power, then it will not be on when ignition is off.
However also note that if you switch to high beam while riding, it will power off!
How exactly do you have it wired up right now - did you simply tap the amp supply wires on to the headlight wires? Which colour wires did you connect to, and where?
Did you ground to the frame, or to the battery -ve, or to a negative wire (like the headlight negative)
As to the noise - can you tell what type of lighting you have in your headlights - is it stock, HIDs, LED or ?????
Is the background noise present if you just turn on ignition, or only when engine is running?
Can you also confirm that the noise goes off when the ignition is off?
Is the noise only present when your source is connected, or background noise even with no source connected?