Brown Dog won't be able to tell you squat about the 2134 innards, they just make adapter boards.
The preamp outputs are NOT working, they just provide an input sneak path of some sort to ground or some other signal path. Have you unplugged all the inputs to the preamp to see if it howls while off but with nothing connected to the input of the preamp?
The preamp outputs are NOT working, they just provide an input sneak path of some sort to ground or some other signal path. Have you unplugged all the inputs to the preamp to see if it howls while off but with nothing connected to the input of the preamp?