What’s the odds of it just being a high quality resampler?
And honestly, RetroArch has an impeccable resampler, Sinc-based resampler (there are others available too but they don’t have the same quality levels). And you can configure the quality of the resampler too since 1.7.1 to be as high or low as you want. Lower settings might give you lower latency though.
Honestly, though, I don’t find the entire comparison to be fair here since these guys have to offer up pretty much no sourcecode, or any kind of proof, of anything they are doing, yet they have lots of open source software to look at and base their work on. So I don’t really like all these hyped-up claims of superiority, same with the latency bragging points where they were trying to claim emulation was inherently inferior when even in that case, RetroArch has next-frame response times and under decent conditions there is no real perceptible difference.
In short, I’d say that while I am not opposed to Analogue NT or their products, and people might derive enjoyment from them and even buy them for legitimate purposes, I do not want to go down this kind of ‘tit-for-tat’ bragging war with them or really entertain any claims of superiority. I do not like this competition-oriented mode that certain youtubers (and in effect their company) seems to want to lead us down.
So I’d say videos like this are non-constructive and unhelpful, especially when they are narrated by people that frankly are not engineers and don’t know really anything meaningful about technology in that case other than what some company CEO regurgitates to them. They might be photogenic and they might be able to present themselves in front of a camera, but that does not mean they know the first thing about writing an audio resampler, or any kind of coding in fact.