given the amp's 25wpc 8 ohms/50 wpc 4 ohms
I would look to efficient speakers as a priority, only the Fyne fits that category.
So, what efficient speaker can you find to consider against the Fyne?
Fyne had a down firing port, I'm not a fan of ports, given your preference for acoustic, I would find something efficient, no ports, low enough for very nice double bass and cello.
Keep in mind, bass is directional, not just the fundamentals, but the overtones,