I put these in my main system about an hour ago and they continue to impress. I can't believe how loud they can get an still remain composed. The SPL meter on my phone pegged at it's limit of 94db, so I don't know how much louder it was getting, but it was impressive. They haven't shown any signs of power compression or strain at these volume levels.
The midrange is fantastic in these, and tweeter is good too, they aren't "dark" sounding, but not bright either, they're really quite well balanced. Obviously they suffer in the lower bass, but I'm running them with 3 subs, so it's not an issue. I'm running them wide open, and I haven't heard any protest from the little 4" woofer, with the subs crossed over at 100hz. I really couldn't recommend these without a sub, or better yet multiple ones, but these really are good enough to be used as mains in a decent system.
It's unbelievable almost that you can get this level of performance for a mere $100. These (with subwoofers) would easily beat a number of other speakers I've owned, including KLH 23's, Boston T830's and A150's, JBL HLS-620's, the 3D Acoustics, Infinity IL10's, my Philips mystery towers. Maybe not in sheer volume, but definitely in tonal balance, and fatigue free listening. But seriously, these things can get way louder than you'd think by looking at them. The sensitivity doesn't seem unusually low either, but I do have enough power to overcome it even if it actually is fairly low.
The rear port can move some air, so right against a wall wouldn't really be advised, I have them way out in the room, about 43" from the side walls and about 68 or inches from the front wall, but they don't necessarily need to be that far out to sound good, that's just my general default position. If anyone is in the market for a bookshelf speaker, even if your budget is well over $100, I recommend giving these a shot. I thought they sounded pretty ordinary a few weeks ago when I heard them in Best Buy, so if you listen to some there, don't let that be the final judge on these.