Going to have a dedicated line installed- What should i know to ask for?

In Australia I would ask for quality 20A cable to be used, also get him to use high quality ac power points, and use dedicated very good HQ circuit breakers in the service box.
 Also if he's licensed for it, get him to tighten all connections (neutral active and earths) check the earth on the water pipe, add an earth spike if he can also , all connections in the service box on both sides of the of the metering unit, also outside on the barge board of the house, and if he's able, on the street power pole that brings in to the house barge board.

Cheers George   

Here in US, each state may have a slightly different code requirements for the electrical work and a certified electrician will and should not deviate from the code, no matter what you ask him to do, of course aside from tightening obvious loose connections. In my state, the only options I had were the choice of the 15 or 20 amp - I picked 20, and the gauge of the (Romex) wire; 10 or 12, and I picked the thicker gauge even though the electrician was adamant that it will make no difference in the sound quality. I also suggest buying some good quality outlets with good tight connections for the power cord. 

A 15 amp circuit is 1800 watts and a 20 amp circuit is 2400 watts. A 15 amp circuit is sufficient!

Im in Brookly NY.  Should have mentioned.