Do I need 10 gauge power cord if I have 10 gauge from panel?

Let’s see  115v or 120v times

15 amps is 1725 to 1800 watts 

your wall outlet voltage might have some

wiggle room 

so yea you need a bigger cable to maximize your audio system 

Eventually frequency is impacted by gauge but not always in a good way.  I would be more concerned with downstream electronics not being able to blow a huge breaker when in distress.  Unless it is some one off like that monster Amp pictured I would not exceed 12 gauge 20 amp service for stereo gear.  For the huge 30 AMP monster AMP I would run dedicated circuit with dedicated breaker.  It already has a 30 AMP NEMA plug to prevent plugging into a standard 110 outlet.

It seems unlikely. Component power supplies are usually built with capacitors lage enough to store power beyond their staedy state demands, and supply power for transients much closer to the output devices than the power cord is.

When your why do people always think the power cord is the last 6 feet? If your amp draws the current wouldn't it technically be the first 6 feet? After all if your amp is plugged in and not powered on how much current is on the 15 or 20 amp circuit? 

@alerrico Wrote:

For the huge 30 AMP monster AMP I would run dedicated circuit with double breaker. It already has a 30 AMP NEMA plug to prevent plugging into a standard 110 outlet.

FWIW: I run the Crown studio Reference 1 Amp on a 240 Volt 20 Amp dedicated circuit with a dedicated 20 Amp double pole breaker, per Crown’s recommendation. 😎

Mike