Right. The track was not available at higher than 24/48 from Amazon UltraHD (you can see this by clicking on the yellow UltraHD logo next to the track in their player. This is somewhat strange since Get Lucky usually is available at 24/88.2.
I use Audacity to capture from WASAPI loopback using the Chord ASIO driver. The driver is configured as 32/192 in Advanced Device Properties in Windows. After capturing about 20s I run Analyze/Plot Spectrum. Since this wasn’t meant to be scientific I then took a screen shot and posted here. That’s why the images vary slightly in size (so make sure you look at the axes).
Everything was captured at the best level the service had to offer for a popular well recorded Hi Res track. If Amazon had had the track at 24/88.2 then it likely would have looked about the same as the Qobuz track. I’ll try to find another track that is available at the same high sampling frequency for both services.
MQA is a lossless way of packing high frequency information into a lower frequency encoding. While it will never (lossless) sound as good as a real Hi Res file, it still sounds really good (to my ears). I do like that we are starting to have some competition in this space.