Hi everyone,
I currently use a Shure SM58 and an iRig to record my grand piano with garage band. .....
Not really the ideal setup for recording piano.
As your recording skills improve you will be wanting to use more channels and better microphones. The SM58 is great for a live vocalist is a rock band who like a hand held mic. Not my first pick for a piano.
What you need is a quality USB audio interface with at least two inputs. However you might thing about getting one with four microphone inputs. The two that I would look at are
the Presonus "Audiobox" series (they make several) and
and Focusrite's "saffire" series of audio interfaces.
I don't know what results you are looking for with the piano. Is this in a very large room with the mic pulled way back to the audience's perspective or do yo want to close mic it from under the lid?
Same question from strings. You can pul the mic back or use one that clips onto the bridge or use a condenser mic on a stand about 12" away. Think about the sound you want. Listen to some good classical recordings and try and decide whig yo like and don't like, do you like the room ambiance or not?
Likely if you are recording in a small, non ideal space, like the typical home living room you want the mice in close so as not to capture much of the poor room refections
Plan ahead, get enough inputs and quality microphones and stands.