i am very happy with my amplified "rumble road" speakers.
they are mounted, with a home made bracket, on the front fork, behind the windscreen, close to handle bars and tank.

just connected power +12V to the grey cable, and i added standard cinch connectors (black & red cables)
so that i could run a cable from my garmin zumo 550 (with SD card for music)
to the cinches hidden below the T.
works very well on cruising speeds, even up to our highway speeds : 130 km/h = 80mph.
at higher speeds the turbulences get to load and i prefer to wear ear plugs on long highway trips anyhow.
Anthony