Actually, I get you. It is not feasible to adjust the volume on each speaker (volume control is on the back) and having a switch could actually saving you from potential disaster, i.e., putting the amp in high gain and turning the volume knob up, while the speakers are powered could possibly cause damage (depends on max RCA output level, of course).
The Origen that I recommended does everything right in terms of functionality, but was lacking acceptable performance at both DAC/Amp. Too bad Amir already tested 2 devices (and both were bad), as I would like to send mine just to check.
However, maybe you could try the
OL Switcher, as other people have recommended. Then you could even send a signal from your phone as a 2nd source and choose which one goes to the speakers.