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

All is useless to do inside the house if the connections to the house barge board and to the street power pole is old and hasn’t been cleaned and tightened in decades.
https://checkthishouse.com/wp-content/uploads/electrical-service-connection-at-the-house-wall-is-too...
These connections can be under ground if a newer (20yold) development area.
 https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcSku4mCRiijbZCgGQkLvqpet38UA9-8t-zZEFuaGMTTApbU... 

Cheers George

This is a commercial HUGE building in Brooklyn. Aside form street power there is a lot going on in the building itself... It is my thinking that a dedicated line with proper ground would still be beneficial. He is charging me $300 per line... Not sure i have anything to lose...

Just want to get as many tips.

Here is a tip: plant corn early. 

This might take some time but there are a few members here who are steeped in this, with one or two in the extreme and they may not see this as I haven't seen them post in awhile.

Having said that, do a search on "dedicated lines" and you'll see lots of discussion on it. It will take time but the few I mentioned will pop up repeatedly and you can zero in on their thoughts and maybe PM them with your particulars.

I can't, for the life of me, remember their names.

All the best,
Nonoise

This is a commercial HUGE building in Brooklyn. Aside form street power there is a lot going on in the building itself... It is my thinking that a dedicated line with proper ground would still be beneficial. He is charging me $300 per line... Not sure i have anything to lose...

Just want to get as many tips.

Well your at the mercy of the buildings wiring. Yes do what you are going to do.

For all your line level equipment, I suggest to use a 110v to 110v isolation transformer. Something like this. And if you use them, plug your mains filter distribution board into the isolation transformer, and your line level gear into the board.
http://www.bkprecision.com/products/power-supplies/1604A-single-output-isolation-transformer.html

For your power amp/s, plug direct into the new dedicated heavy duty wall outlet. (NO power conditioners, they sap the dynamics.)

Cheers George