Interesting topic. I generally avoid the stereo speaker threads as a lot of it is very subjective. I have found myself lately looking for more volume and better sound so I have been reading the stereo threads.
I run an aftermarket radio in my bike, a Pioneer AVIC N2, which from what I have been told makes decent power for a head unit only. I have tried Hog Tunes, Pioneer, JVC, Kenwood, Biketronics/Hertz and J&M speakers so far. They all have their pros and cons. Not a single one has held up for more than a couple of months. Now I'm not blaming the speakers, it is I who turns the volume knob just as far as it can go. It is my understanding that I'm distorting the speakers and killing them. Thus an amp would/may solve some of my problems. Pez from Hog Tunes was straight up with me and told me his amp won't be much better than what I already have. I need a larger amp, the Biketronics unit is one of the ones he recommended.
So the search has begun, looking for an amp. Yes I can order the Biketronics amp however I wanted to see what may be better. This led me to the HDForums as there are several guys who have some serious stereos in their bike. I read their posts and after doing so continued looking for an amp!
Part of what is harming me is running only two speakers. It's a Roadie without lowers or a tour pac. I have considered installing two more speakers in the fairing facing the bars. I've yet to measure to see if this is possible.