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

JasonBourne52

 the benefit of a 10 gauge wire from the electrical panel is to achieve a benefit from lower impedance and Power availability for all those Quick changing frequency needs. Clearly there's enough power to run the device but that's not the point.

The power cords would be connected to 600 W mono blocks.  
 

The biggest improvement is in reducing resistance per foot.  If you ran 30' of 10 gauge it's still better than 30' of 12 gauge.

Just make sure your breakers are right sized for the end use.  Meaning 15 or 20 Amps.

I have been in this hobby since 1976. I have yet to hear a sonic difference between any power cords! I know enough about physics and engineering to question the veracity of the "golden ear" claims for the superiority of one power cord over another. 

@jumia : I understand the necessity of having low resistance in a power cord for transient peaks. Shunyata designed a device to measure this using transient speed compared to power in watts. They found that transient speed became a factor (slowed down) only when the 10,000 watt level through a power cord was reached! So below 10K watts a 14 gauge cord is perfectly fine! No deleterious effects!

My father's table saw would sometimes trip the 15amp panel circuit breaker when cutting plywood. I doubt your pair of 600 watt amps would do that even at clipping!