Probably a stupid question but Carvin lists some amp heads such as the BX1600 Bass Amplifier Head followed by the B1000 Mono Block Bass Amp Head (same page as link). What does that mean and why would someone use "Mono Block" as opposed to the BX1600 (Or other similar amps)? Does it mean that the BX1600 et. al. & etc. are "Stereo Block" amps?