Below the transition frequency the room, not the loudspeaker, dominates sound quality.

Evidence

Figure 5.2 shows that in small rooms, low-frequency resonances are significant problems. They are different in different rooms, and different for every loudspeaker/listener arrangement within a room. The loudspeakers provide low-frequency energy, but the room is the dominant factor in determining the quality of the sound below the transition frequency. — Toole, Floyd E, Sound reproduction- the acoustics and…, 486