Dedicated Line Advise

I believe you would want both lines on the same phase within the box. I would use one for digital and one for analog. Would you consider adding 2 additional lines? One could be dedicated to amplifier.  

Lowrider, somehow I lost tract of your post and not responded. However seems you have gotten the info you requested, and more, from those that are far more knowledgable than I. Lots of great info here, thanks for the post. As pre willie, I have my audio lines at the bottom of my box and the dual phase breakers at the top. 

I bought a home for my kids to live in while going to college. Built in 1923, it had a new box installed, actually 2 boxes. One outside box that carried a mains breaker which fed a interior box for the home. Never seen this before. If wanting to work on the interior box with no fear, simply throw the breakers on the exterior. Wish I had used this system when I built my home in 2000.  Now, if I wanted to restructure the breaker positions in my home box I would have the utility company remove the supply meter for the day.

Cleeds, I agree it is not necessary. However my Square D service panel in the home I built has the input posts exposed such that it would be possible to contact one when swapping around several breakers. 

Now, i don’t know what it would cost to remove/replace the meter.