In this same situation (and believing, without ever conducting blind/ABX tests on the matter, that extra connector for an extension cord degrades the sound) I bought 15ft cord from www.stefanaudioart.com
Woo Audio 3 with NOS Mullard tubes and Senn 650 were at the ends of this cord. Sold the whole rig a few years later, remember I was surprised that resale value for the cord was very decent
Woo Audio 3 with NOS Mullard tubes and Senn 650 were at the ends of this cord. Sold the whole rig a few years later, remember I was surprised that resale value for the cord was very decent