FIR filters can achieve perfect linear-phase response — all frequencies are delayed by exactly the same amount, preserving transient timing and stereo imaging. This makes them ideal for room correction, crossover filters in high-end monitors, and mastering EQs.
The trade-off: achieving fine low-frequency control requires many 'taps' (coefficients), which adds processing latency. A 65,536-tap FIR filter at 48 kHz adds 682ms of latency — fine for playback, unusable for live monitoring. IIR filters achieve similar frequency control with far fewer taps but cannot maintain linear phase.