Re: Sena SMH10 Speakers
I don't have experience with the Sena, but I use the Scala Rider. Because of where the speakers are mounted they are necessarily small, which translates to very thin sounding. Also the power that the headset is pushing them with is limited. You may be asking a bit much of them.
I can tell you that positioning is everything. You want the speakers sitting right on your ears in the helmet and pointed right at them. If they're just a hair off from straight at your ears you'll lose what little bass they do put out. Depending on your helmet you may even want to add some padding behind them to close the gap on your ears. I spent a few hours in my living room getting them situated in my helmet before I got the best possible sound out of them.