I'm currently using an LM2596 DC-DC converter (as part of a break-out board) to power my TDA7318 mixer chip, which in turn gets audio signals from a sound HAT and an FM radio module. Input voltage is 12 V, output is 9 V. As I have experienced some trouble with a very high noise level on the TDA's outputs (in fact, you can hardly hear the sound itself), I've got the following question: Is the LM2596 good enough (in terms of noise / ripple / other impurities in output voltage) for feeding power into audio circuitry like the TDA?
UPDATE: Here is a hand-drawn schematic of the mixer and its connections. The amp isn't depicted here as I haven't implanted it yet. Instead I'm using headphones to listen to the mixer's output:
UPDATE #2: Replacing the switching regulator with a linear LM317T one did not help: The noise remained as it used to! The only cause I can't exclude is the wiring. The orange wire on the top right delivers +9VDC, its green neighbor is the ground wire. The black thing named Visaton is one of the coupling capacitors. See this picture:
UPDATE #3: I've run my oscilloscope over both DC–DC converters and made one 1-second video of each output: