Nearly very good!

Slightly painful (and time consuming) start due to various bugs in the software (e.g. you can select any audio input from your interface for the mic signal as long as it's input one...!), but once I got through to the calibration stage things went much more smoothly.

Things to improve:

- Archiving (saving) and loading previous measurements for comparison and reversion is absolutely essential. If you want a calibration with and without the sub, or you use you monitors in more than one location, this is really essential.

- A quick means to switch between presets is also very much needed.

- Don't forget to apply the calibration before closing the app, or you will have to redo all your measurements!

- Measurements should be salvable independently too, so they can be reused to generate a different eq curve.

- Would be nice to be able to select any input channel, as the interface suggests ;)

- There is also a bug regarding system gain, whereby you have wait a few minutes after assigning your speakers to Left/Right position before testing the system gain or it will repeatedly fail. There's no onscreen indication as to why this is failing.

- I also managed to get my monitor indicators to flash forever by clicking the ID buttons and then going to next screen before they stopped flashing.

- Would be great if the audio IO UI had an input VU meter to help identify when the mic channel was correctly selected and working.

Results: Moaning aside, the results are very good and I think this is an essential bit of kit if you use your KHs for anything critical. The low end was never right, even using their ipad algorithmic calibration wizard (which did help quite a lot over the rear switches) and I had limited trust over the low end of my mixes. Now it sounds really smooth and open across the entire freq range which is great!