Will I benefit with 20 or 15 amp dedicated lines

A 15 amp is plenty,you will never need a 20 amp it would be total overkill,a 15 amp is the correct type for your gear.

Kitegod,

The biggest expense of the job will be for the labor of the electrician. Install 20 amp branch circuits. #12 awg NM-B cable minimum.....

Make sure the new branch circuits are installed on breakers that are fed from the same Line, leg, in the electrical panel. Preferably not across from breakers that feed noisy AC loads such as motors, microwave, ect.

In my opinion,humble as it may be,dedicated lines should originate at the main panel not the distibution panel.I would run 20A circuits,only a few dollars more for materials.You might not need them now,but,you never know what you needs will be in the future.Others may disagree and that's fine with me.

Definitely 20A. circuits with the 12g.wire w/ground . Use copper not aluminum wire .

And I would suggest that you have them installed with an isolated ground . That would be a seperate ground from the rest of your electrical system with the grounding rod at least 6ft. away from the original . This will assure that you do not get any noise from other things in your home as mentioned above . This is the type of grounding system used in hospitals and computer rooms . You may need to hire a 'commercial' electrician to find one with experience with this type of grounding system . I did .

Just Google isolated grounds so that you will know what is involved with the installation procedure . It is not that difficult , just different .

Oh , and having two seperate lines will allow you to seperate your digital items from your analog items .

Good luck .