slight tweak, today.
I had an extra prototype box (heh, who am I kidding, they are ALL prototype looking boxes) and I needed a way to control my subwoofer so I built another relay attenuator but set the dB spacing to be 0.1dB instead of half dB. its 8 relays = 8 bits = 255 and so 255 / .1 = 25.5dB as the max range. more than enough to 'fine tune' a powered subwoofer's input level.
now I can sit on the couch and isolate the sub or the main speakers and set their level controls to half a db or even .1 db.