Steve,
I would like you opinion on whether the Short Block may solve an issue I have with the hum in my system. I used to run my iMac from a different outlet (breaker box line) than the OR5 and the rest of audio gear via: USB into an OR5 - I2S cable - W4S Dac2 - single ended tube preamp - Jensen Isomax RCA to XLR isolator (PI-2RX) - Solid state balanced amplifier. There used to be some hum but very low in level, it only could be heard with the ear close to the tweeter. Over the week-end I took your advice and connected my iMac to the same breaker line as the rest of my audio gear. The hum level can be heard from the listening positions and is quite loud. I isolated the problem to the connecting/disconnecting the USB cable form the computer. Even after I shut down the iMac altogether and the USB is still plugged into the iMac and OR5 the hum is still present. When the USB is unplugged, with or without the iMac powered, the hum is totally gone. The USB cable is 4 meters long and runs next to the power cable for the iMac. My question is, do you think the shortblock may solve this issue? I figure it may be caused by the shielding or grounding of the USB cable and since the shielding is not affected by the short block it may not have an effect. Thank you for all your great work!