I feel that pretty much all the audio analysers are 24bit adc's with large signal to noise ratio's of upt 120dB. Plus many different audio/Blue tooth/I2s/rub & buzz and headphone measurment applications. They all perform both digital & analogue domain measurments The APX555b offers 1.2M FFT's from dc-200Khz.
Does this justify the cost, for hobbists no it's out of the equation. Although these are mainly geared for production line testing with they ability to set up multipule tests in sequence mode
We have four audio analysers R&S UPV66 all options / AP APX555B most options / Prism sound D scope series III / Standford research SR1 (under rated in my book).
IMHO the Picoscope 4262 is also a great device for audio investigation up to 16 bits of resolution 16Mpts buffer, decent analogue genny and really good FFT's and for the cost its decent, a couple of us on here use them regularly for good reasons.
As good as all these audio anaysers are, I still use the Lecroy attached at the same time to the signle ended analogue outputs using both time & frequency domain above the usual audio BW restrictions, you can see a lot more going on further up the rev range if you like
![Grin ;D](https://www.eevblog.com/forum/Smileys/default/grin.gif)
This peaked my interest although purely an analogue domain unit, its features and size make it ideal for a portable in the field unit.
https://www.virtins.com/RTX6001.shtmlWould also agree with the HP 3561A as well if you have the spa on the bench.