TPA2017D2 Stereo Class-D Audio Amplifiers Texas Instruments TPA2017D2 Stereo Class-D Audio Amplifiers feature SmartGain™ dynamic range compression (DRC), automatic gain control (AGC), and noise gate. The SmartGain functions of the TI TPA2017D2 are configured to automatically prevent distortion of the audio signal and enhance quiet passages that are normally not heard. SmartGain is a combined AGC, DRC, and Limiter that protects the speaker from damage at high power levels and compresses the dynamic range of voice or music to fit within the dynamic range of the speaker.