Ismo (OH2FTG) has praised the STM32's ADC quality multiple times, and I finally decided to give it a go.
I usually stick with Waveshare RP2350-Zero boards, but the RP2350 ADC performance is limited to under 10 ENOB.
With the STM32H562RGT6, we're able to achieve ~13 ENOB using 16× hardware ADC oversampling, with potential headroom to push this even further.
By sampling the Si4732's SSB output using the STM32H562RGT6 ADC and exposing the samples to the host via a "virtual" USB UAC-2 device, we get the following RX results:
Not bad!
As usual, we stick with non-optimal antennas (a 10m-long EFHW in this experiment) to better emulate POTA / SOTA / man-portable operating conditions.
Yes, a high-quality narrow-band QSD IQ SDR will often outperform wide-open, ultra-wideband SDRs in single-band performance ;)