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

I doubt you will hear a difference. But if you will feel better, and want bragging rights, buy a couple 8 ga PC’s. 
 

so, you have 8ga from your box :) to outlets,?…..I would probably grab a medium cost 8ga cords, more money does not mean 10x better. 
 

use your best judgement. 
 

years ago, I bought 30feet of 8ga speaker cable, I have to cut them to fit in the banana plugs. 
 

NO! Because even a 14 gauge power cord is rated to handle 15 amps/ 1500 watts. This is the same rating for the typical breaker box/AC outlet found in most homes. That's a lot of power! Increasing the size/diameter of a power cord is only required if you plan to use an arc welder! Then you need a lower gauge/thicker cord. For a 200wpc amp a 14 gauge cord is perfectly fine. You don't need a garden-hose size power cord!