DIRAC CORRECTION
The Dirac room calibration used here is a bit more complicated than the normal systems on AV receivers, because you have to run it on a computer — though either Windows or Mac is fine. You can not to use Dirac at all, and just set the distances and levels manually, but Dirac tunes the system for room and speaker anomalies — in part — and also adjusts phasing to ensure a coherent wave front. It also sets levels and time delays.
The measurement microphone plugs into a USB audio device, and you plug that into one of the spare USB sockets on the hub plugged into the receiver. You download the Dirac Live LE for NAD software from the NAD website and install it (I had to insist to Windows at a couple of points that it was okay, I was letting it access the network and so on). When you run the software, it scans your network and finds the NAD amplifier. You follow the instructions built into the software — it’s all a bit old-fashioned and clunky, but it works — to makes sure the levels are set to a suitable level, and then you let it rip. It likes to measure nine different positions. When you’re finished, it shows you measured graphs of all your speakers along with the NAD target EQ curve. You click ‘Optimise’ and wait while your computer calculates the adjustments. This will then show you the adjusted result for your speakers (assuming that they actually respond as calculated). Then you drag the results to a column in a chart. That downloads the DSP adjustments to the NAD amplifier. Then you click ‘Enable’ (as I said, it’s a bit clunky), which switches them on.
Now you will recall that I said that it tunes your system ‘in part’. That’s where the LE for NAD part of the software name comes in. This version only handles from 20 to 500 hertz. The full, paid version ($US99) covers the full audio bandwidth.