hogtunes will not work on a road king because there is no factory speaker to replace. Google rumble road speakers and two wheel tunes, there is also boxes that hold a radio and speakers that mount to the windshield, and the fugly hd handlebar radio. A custom system is always an option.
To answer more specifically to the question asked, if you were going to run a head unit like in a car you would not need an amp because it is built into the head unit, but if you were going to run an mp3 player like myself, a satelitte radio receiver, or a fm walkman, then you would need to amplify the output with an amp. Truth be told, if I did not have a tachometer mounted, I would have gone a different route. That route would have been one of these... http://www.motorcitycycle.com/products.html. THere are a few different variations on the same idea out there, but i like it cause you can be more involved in your choice of components and i all comes off with the windshield. I never ride with my windshield but i would have trimmed mine down tiny so I could have used the radio. The flaw with this system is that you would loose all setting on the radio each time you took the windshield off. All in all, not really a big deal for most.
i have a creative micro zen 5G.
when i listen the music i put him inside the bag of the windshield and the speakers will be on the handlebar.
i don't interested for the size of the speakers or if they are fixed, i need only to listen music without headphones ;-) :cheers:
I use the rumble road amplified speakers with a roady2 xm radio and it works great for me. I can hear them on the highway, but when I go any distance on the interstate, I'll unplug the speakers and plug in a set of headphones so it is easier to hear over the wind noise.