Should Subwoofer Be Plugged Into Same Circuit?

I’m glad you guys jumped into this convo because I have another question. 
Notice I said same circuit.

i need to branch an outlet off to reach the sub in the corner of the room. 
I don’t see why the sub would have to be plugged into the exact same outlet vice a branch outlet in the corner where there is only the two outlets in the circuit.

please advise.

My guess is that you'll be ok plugging the sub into a different outlet than the rest of the system, on the same circuit. Assuming (per the reference cited in my previous post) that the wiring between outlets is Romex or some other wire type which has the safety ground conductor symmetrically placed between the two current carrying conductors, or alternatively has them all twisted together.

The only way to know for sure, though, is to see how it works out, as susceptibility to ground loop issues is also very much a function of the design of the specific components.

Best regards,
-- Al

Thanks Al! So why is a 20 amp circuit recommended over a 15 amp out of curiosity? 

In addition, @almarg correct me if I'm wrong, one of the receptacles needs to be grounded to the service panel, not self grounded. If there are two separate runs of Romex, then both need to be grounded to the panel to help prevent a  ground-loop. This may also lower the noise floor.

... why is a 20 amp circuit recommended over a 15 amp out of curiosity?

My understanding is that 15 amp circuits are often wired with 14 gauge conductors, although they can be wired with 12 gauge, while 20 amp circuits must be wired with 12 gauge or larger. For a given amount of current 12 gauge will of course produce less voltage drop in the conductors than 14 gauge, resulting in a slightly higher voltage being supplied to the components. (Although if the line voltage that is supplied to the particular location is near the high end of its +/- tolerance less voltage drop in the conductors could conceivably not be preferable, depending on the design of the specific components). Also, of course, with a 20 amp circuit and breaker there is less chance of overloading the circuit and causing the breaker to trip, for instance if the power amp and/or the sub draw large amounts of current for significant amounts of time, during high volume musical passages.

@lowrider57
... correct me if I’m wrong, one of the receptacles needs to be grounded to the service panel, not self grounded. If there are two separate runs of Romex, then both need to be grounded to the panel to help prevent a ground-loop. This may also lower the noise floor.

I think your words "not self grounded" are referring to the fact that it is preferable for the safety ground wire to not be connected to metal conduit at the outlet, and that is correct per my understanding. Regarding that also see page 191 of the reference I linked to earlier, which discusses "isolated ground" receptacles. Note that using Romex to connect to a non-isolated ground receptacle accomplishes that by its nature, since there is no conduit.

And of course neutral and safety ground for all runs must be connected together at the main service panel, and they should be and hopefully will be connected from there to a nearby earth ground.

Best regards,
-- Al