I just made my first attempt at making a Bluetooth Stereo PCB, and it was okay. This is a Class D Audio Amplifier, with the main IC being the TPA3122D2. O was planning on powering it through USB C, with a Op Amp Circuit that would disable the speaker if it received an input voltage of under 12V. But I had to settle for a 12V wall adapter since the USB C 12V input was creating issues with how the speaker operates. The one big issue is that there is a low frequency static sound on the speakers that is present, even when there is music is playing (hard to hear, but it's there). This isn't related to the Bluetooth module since it's still present without it. What are ways that I can improve my design in order to eliminate this?