[asdhtjkujh]

Slight tangent, but does anyone have experience with recording hydrophones in excess of 192khz? Last I checked, most of these are specialty devices with high price tags.

Recording full-fidelity whale or dolphin sounds (amongst others) requires using a higher sample rate than is available in most consumer-grade equipment. There's a lot more information down there!

[hecanjog]

I've used audiomoths for this. They can be configured to record at sampling rates up to 384kHz and be deployed with waterproof cases: https://www.openacousticdevices.info/audiomoth

[DoctorOetker]

Why not use the ADC's used for CIS (contact image sensors, the linear sensors in consumer-grade scanners / photocopiers)?

For example:

12 MHz (i.e. 12 000 kHz) sample rate per channel, 4 channels, 16 bit ADC:

https://www.akm.com/eu/en/products/mfp-lbp/ak8471vn/

single digit dollar unit prices:

https://octopart.com/search?q=AK8471VN&currency=USD&specs=0