The MA6100 is an integrated amp, meaning that it combines a preamplifier with an amplifier.
Nowadays, most amplifiers are integrated, but that wasn't always the case. For instance, my 1957 Heathkit W-6M amp is nothing but an amplifier, and it relies on a preamp such as the Heathkit WA-P2 to switch between different input sources, control volume and tone, and provide an initial stage of amplification.
The MA6100 provides the same functions in a single package. It is a stereo amp, providing 70 watts per channel, with provision for two sets of speakers as well as headphones. It has various tone controls and it accepts as many as six inputs (Aux, Tuner 1, Tuner 2, Phono 1, Phono 2, Tape Head).