Best presentation sonically is needed these days as everyone is making music on the computer.
Depending on the genre you are going for even getting heard by a semi sized indi label is not easy.
You need an angle, and at least to set up a rapport, as cold calling with demos will get you absolutely nowhere.
You need some kind of contact at the place so that when your demo hits the inbox or lands on the doormat, they already know who has sent it and are expecting it.

Good visual presentation helps a lot, as well as offering a full package, good gig history, proven fan base etc, all these things help massively.
I played the label circuit many years ago and finally got signed by Beggars Banquet, and the whole game is nasty but you do need to make sure you have everything sewn up and sorted before you send that demo, or you are wasting your time.

Also reproduction in a studio is a possibility depending on the size of the label, but bear in mind advances almost don`t exist any more, and you will end up paying for pro studio time either yourself, or out of your advance anyway.