Here's a funding route I love for all sorts of situations: Start small, and go directly to your intended audience.
Use a pre-sale campaign with a tilt mechanism (one that requires crossing a certain threshold before anyone is charged - so that you can ensure you will cover your costs and not leave anyone with unfulfilled obligations).
In this way - you are raising funds and marketing in a single bound - rather than dividing your efforts in two.
Ultimately, if you raise funds from an investor (not sure where Chamber Music Concert Investors are to be found outside the usual patron of the arts set, but that's a different issue) you'll then need to repay that investment from the sale of tickets, boxes, memberships, packages or however you intend to charge your end audience.
Happy to expand on this notion and tie it to your specific goals - I'll just need some more details.