There are some questions that may help narrow down what you are looking for. Are you looking for someone to design the systems, perhaps putting that design out to bid or adding it to your current contractor's scope, or are you wanting a company that will design the systems, sell you the related equipment and install everything? Where are you in the building process, it still a design on paper or are you well into the physical construction? Would you like the company to also potentially address acoustics? Do you have a budget that you are willing to share? Is your Architect open to working with whomever you choose or do they have some preferences?