Here is my triple blind setup. Each DAC has its own pot (JBL Nano Patch). These pots are used to match levels. The outputs from these pots are then plugged into a switch. The back of the switch is occluded so that I cannot see the wires. While I am out of the room, my wife or kids plug or change the outputs from the pots into either the #1 or #2 outputs without knowing which is which (it's a rat's nest back there). Going forward, we if feel this is not enough, we can occlude the back of the DACs and pots to protect against telepathy. Just in case one of my family members knows which wires came from which DAC and wants to me buy a specific DAC. Then they can beam "#1" or "#2" into my head to influence me. We wouldn't want that happening. I'm not against quadruple blind tests. The procedure will be as follows: I will learn the sound signatures of the DACs using "flawed" sighted tests at my leisure. The test will be set up I will be able to play any recording which I choose. I will be able to select either button #1 or button #2 at any time that I wish. I will then "guess" which button number is which DAC. I will also take notes that how #1 differs from #2 or vice-versa. This will be confirmed by my pressing the mute button on the appropriate pot.