Recently I met an old altec system that was still kicking in a local theatre. It consisted of a pair of A7s and a pair of 128b amps fed by a 1567, into which they ran a feed from their digital movie projector and the outputs of a mackie mixer for live events.Aparantly they just had all the components overhauled and plan to keep them in service indefinitly. What got me about the setup were the 128b amps. Im familiar with the 159x solid state stuff and the 156x tube stuff but ive never heard of 128b amps. What were they designed for, and how are they different from the 1568 and 1569?