For me, and I’m happy to hear contrary opinions, what it seems to suggest is the following. Firstly, Amir’s ‘limits’:
Continuing the series on learning measurements, I recorded one last night on power amplifiers. Alas, my external microphone got disconnected and internal one to the camera was used. So the sound quality is rather poor. A personal note: as you may know, I don't allow advertising in my...
audiosciencereview.com
He suggests that the limits of human audibility are THD+N of -115 dB and SNR of 108-114 dB. I’m sure he’s right - the limits of human hearing are well-documented.
But the A500 falls some distance short. So what we’re into is the gap between the theoretical limits of human hearing (presumably listening to distortion of a sine wave on a pair of headphones - probably closed back, so no other sounds) and the real-world limits when listening to music.
When I read Amir’s reviews, I’ve always focussed on those figures for DACs amps. But I’d like to see more focus on real-world limits, as well as theoretical ones.