All existing wires and cables exit through the top of the breaker box. For the dedicated line he exited directly through the side of the box with Southwire Romex 10-2 wire.
He kept the wire run completely isolated. The run enters a junction box and two Southwire Romex 10-2 wires then make their way into two Furutech GTX-D (R) wall receptacles.
I have an amp and phono pre occupying the two outlets on the left receptacle and my turntable occupying one outlet on the right receptacle.
Regarding grounding, nothing additional was installed or done. The electrician grounded the line with the existing house ground.
there is a noticeable difference in noise floor, dynamics and less line level noise. These particular outlets take quite a while to break in. Some suggest 600-800 hours.
good luck with your planning/install.