Please do show 1 kHz square wave response with all PCM and DSD resolutions/filter settings. For the 96 and up, you can use 6 kHz or 10 kHz square wave in order to show the superiority of DSD's pulse response. Intermodulation outside audio band measurements should also be presented; I do not agree with
http://people.xiph.org/~xiphmont/demo/neil-young.html at all, but the arguments are valid and hirez equipment should be free of this kind of (mis)behaviour by default.
Making those measurements will be very time consuming, using the AP2 is pointless as in many filter settings the AP2's own impulse response dominates that of the iDSD, so it would have to be done scope and photo on phone. With so many sample rates and DSD flavours in the nano/micro, we must bow out, just too much work (making all these flavours just came back to bite us in the posterior.)
Plus, it would actually not show anything new over the White noise graphs. IMD outside the audio band is down to the filter response.
The graph shown includes these using the "Standard" filter (the one we recommend to use for measuring gear, but not for listening). Any IMD above the noise floor of the AP2 in "wide” mode would show up as noise rise or just as increased noise floor.
The line around -120dBFS where the "white noise” graphs flatten out is the noise floor of the AP2 (particular model we have) when presented with a full scale signal.
So to the measurement limits of most models of AP2 there is neither ultrasonic noise leakage or IMD.
384KHz (so no filter)
iDSD nano Squarewaves (150MHz HP Digital Storage 'scope):
96KHz - minimum filter