If the problem is the volume of MP3 music or audiobook files, you can change the gain of these files with a free program called MP3Gain. Also, I use earphones instead of helmet speakers, which has the dual advantage of protect my hearing from wind noise and doing a better job of transmitting sounds into my ears so that lower volumes can be heard well (I use a Chatterbox xBI, not Sena, but the principle is the same).