My room is 20' x 20' x 9'. Two adjacent walls have large openings, so the effective volume is larger than the measurements indicate.
I use a digital source.
The loudspeakers are specified at 92 dB with a minimum impedance of 10 ohms.
I listen to music at a volume that doesn't exceed 85dB, which is typical of what I hear when I attend the opera, seated within 15 rows of the orchestra pit.