Has anyone tried this kit? Its cost is similar to Khozmo set. A big advantage would be that there are no contacts. Audio signal goes through light controlled resistors (which are calibrated by on-board firmware). The inputs are also controlled by the same board. The price depends on how many inputs are on the board. I know that Tortuga makes passive preamps and they have very good reviews. It would be nice to hear your opinions. I am thinking of building a tubed buffer with remote controlled volume and inputs, hence my interest in this kit.