The metal jacket of the BX cable acts as a ground. Being in contact with the metal box, you can buy a "grounding wire", usually green with a threaded screw at one end, and screw that into the back of the box. Then buy your outlet of choice and hook the other end into the outlet ground terminal. Of coarse, if doing it yourself, don't forget to disconnect power to that circuit.
"Absolutely have an electrician run a new, dedicated line, or maybe two, just for audio. It usually cost less than $100, and is one of the best bang for the buck upgrades out there."
An electrician come out to you house and run 1 or 2 dedicated lines for less than $100.00? I would imagine the material alone would exceed that (depending on distance from panel box to audio outlets).
"Absolutely have an electrician run a new, dedicated line, or maybe two, just for audio. It usually cost less than $100, and is one of the best bang for the buck upgrades out there."
An electrician come out to you house and run 1 or 2 dedicated lines for less than $100.00? I would imagine the material alone would exceed that (depending on distance from panel box to audio outlets).