Modular test system: the signal tracer module revisited, now with DSP ADAU1701

The first module I designed for my modular rack was a signal tracer, it works fine but the audio amplifier was very sensitive to digital noise around it. I decided to design another one, this time more attention to noise suppression and the use of a DSP module. It seems overkill but I had several spare DSP modules I bought for a few projects that I did not go through with. The ADAU1701 (1401) is an interesting one, cheap modules, simple and free design tools, check out my video on the CB speech processor for more info on this DSP. The circuit has a coupler cap, relay attenuator and 2x input pre-amplifier, the DSP has the volume control, an additional amplifier, fixed and adjustable low and highpass filter, envelope detectors for VU meter and overload at several points, provides output to the I2S amplifier and an I2S channel to the ESP32. The module has a scope and spectrum analyzer function, an adjustable filter, a monitoring feature and a connector for future developments such as active probes. Let me know if you have suggestions for other functions that can be added in software (or probes).