You might be able to do two swivel chairs in that space, or a small chair in the nook under the TV. You will want to measure to make sure anything you buy won't be too big for the space, but we do not recommend a sectional, unless floating it in the space, facing the fireplace and then have to chairs behind the sectional facing the door that opens.

Another option is 4 swivel chairs around an ottoman:

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Smaller sofa/apartment sized sectional with armchairs or swivel chairs:

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Seems like you need specific seating options for the players of those stringed instruments. What do they find comfortable?

Haha, love that you made that comment. It is true. We usually sit on one of the blue chairs. We would like to add more seating for entertainment and well and prefer a cozy feel.