Here's what Arc's instructions say about the ground wire:
The Ground!!!Warning: Read this Carefully
The ground wire should be connected directly to the chassis of your vehicle.
Find a location close to the amplifier . . .
Source: Page 2 of these Arc 125.2 installation instructions, emphasis and punctuation from original, from Arc's website:
http://www.arcaudio.com/product-pdf/miniv2.pdf For those viewing this thread who may want information on where to ground an amplifier on their bikes, there are ground studs under the seat as TIF2 mentioned, and one on the left side of the upper triple tree. Grounding to the frame/chassis is also recommended by J&M and Rockford Fosgate, as well as the guy who writes the website referenced below.
For those viewing this thread who may want information on setting amplifier gains, this link is useful:
http://www.bcae1.com/gaincon2.htmAs I mentioned earlier in this thread, I'm not a tech or audio professional.
Carl
Edited to remove the reference to the original post.