The hardware in combination with it´s associated software package ´Waveforms´ allows the AD2 to also function as:

- Spectrum Analyzer, 2ch, noise floor, SFDR, SNR, THD harmonics and more

- Network Analyzer, 1Hz-10MHz, Bode, Nyquist, Nichols plots

- Impedance Analyzer 2-Wire, 50pF-500µF, 10µH-1000mH, 1Hz-15MHz

- Voltmeter, 2ch, +-25V

and as Logic Analyzer, Pattern Generator, Data Logger, Protocol Analyzer, Curve Tracer etc etc.

Pretty impressive, aint it? The Question therefore is what the limitations of each function are.

It´s pretty obvious that the ranges are quite restricted, if You use the AD2 without externals.

With externals (power supplies, signal conditioning, etc) it gains on useabilty at the cost of convenience and of course price.

As an Audio guy I`m rather interested in the ´analog features´ Spectrum, Network and Impedance analyzing .... but is a Cap-range of up to 500µF sufficient for testing power supplies? Are 10MHz enough for a decent check of a spectrum? Wouldn´t it be nice to have Smith chart available?

As far as I know the Waveform software can run on any PC and with their soundcards.

As most soundcards nowadays feature 24Bit of resolution and up to 192Khz clock, just add some peripheral devices (amplifiers, power suplies, etc) and You have almost professional´s measurement capability below 100kHz.

Decent standalone benchtop Spectrum Analyzers start from a few kHz, spanning up to a few GHz.

The recently introduced Siglent SVA1015X and SVA1032X  for example are Spectrum Analyzers and optional Vector Network Analyzers ranging from 9kHz to 1.5GHz, resp. 3.2GHz (fully equipped they range well >2k€ of course).

Benchtop Network and Impedance Analyzers all seem to be well outside of a Hobbists budget, even when offered used.  A Keysight E5061B with LF-option (>5Hz) will disburden You from ~35k€!

So Yes, the AD2 still sounds interesting to me .... the more so after discovering Nifty´s Blog at http://designideas.cocolog-nifty.com/blog/  Its written in japanese but a online translator did its job nicely.

Nifty seems to use the AD2 extensively and the results seem perfectly decent and useable to me.

And let´s finally not forget that this little item is a mobile device also. Add a labtop and the breakout boards and You have a complete lab at hand ... nice for presentations, workshops or fairs or ......

That convinced me that the AD2 can be more than just a educational device or slightly costly gimmick.

in the meantime I could run first tests ... and Yes, the little Thingie is more than it looks and is alot  of fun too.