Using the HTD MC-66, button press requires “repeat on hold” for sending repeating commands (volume, bass, treble), otherwise the unit will “freeze” all zones until customer reset the pre-amp (off/on). HTD Tech support recommended, at least, a minimum default timing of .5 seconds. My problem is that customer not necessarily are following the instructions, pressing the buttons repeatedly, while “flooding” the system (signal freezing, requiring resetting). Any suggestion on how to solve this particular problem? As a comparable features and price point, Russound offers the CAA66. Any experience regarding this issue? Can anyone recommend a similar controller, with or without built-in amplifier?