KS 125.2 BX2 - Arc Audio 2-Channel Mini Amplifier KS 125.2 BX2 - Arc Audio 2-Channel Mini Amplifier he BX2 technology gives you big bass and improved low frequency response without the additional physical demand on your speakers Bridge Auto detect mode (Autosense Turn On) Ultra compact chassis design allows for installation in small vehicles and inside the factory fairing of most HD brand motorcycles Class H switching design allows for maximum sound quality, performance and reliability without distortion and lack of performance of digital Class-D amplifiers.