Tom,
Glad Sam was finally able to reach you. I discussed the problem with him and when I described it, he told me he was having the same problem. I have never experienced this problem with my unit, but I am very careful to discharge my static build-up on the Target equipment rack and not any of the equipment. Static Electricity is an extremely high voltage with very little current flow. It can't kill... anything but electronic equipment! Especially units that have solid state devices in them... such as PCs, preamps, DACs, etc.. It does this because the discharge is through tiny fragile circuit paths and the discharge follows the path of least resistance, wreaking destruction on the circuits it happens to pass through.
There are sprays that are effective when used on carpets and cloth seats that can really cut down on this type of static electricity. You can also get in the habit of discharging yourself before touching the equipment.
In the instance of power surges caused by loss of power and subsequent return of power, provision is usually made within the device to protect the circuits. Power switches usually have provision for some suppression of surges when they are operated (On/Off) and most equipment has some form of surge protection built in.
Plugging in or unplugging a power cord with the switch in the ON position may well bypass the switch/power supply protection and cause other protection to engage, as it did in Tom's case. In this case, muting the output, keeps the surge from blowing downstream equipment, especially speakers! I suspect that the equipment has to be re-booted a couple of times for it to revert to its normal operating condition. Better an over-sensitive muting circuit than one that's just a "little too slow".
It is always worthwhile to have the more robust surge protection of a device (power strip) specifically designed to offer more protection than usually built in to equipment!