When selecting a professional amplifier, you must prioritize Output Power (RMS) rather than peak power to ensure sustained performance. Look for a Signal-to-Noise Ratio (SNR) of ≥100dB to guarantee clear audio output. Additionally, verify the Total Harmonic Distortion (THD) is less than 0.1% at rated power. For high-end applications, ensure the unit features Class D or Class AB circuitry for thermal efficiency and audio fidelity, and check for 2-ohm or 4-ohm stability depending on your speaker configuration.