Thanks for the explanation and confirmation that it's the expected behaviour of MacGuffin - interesting that no one has commented on it before.

@Support_AODYO - here's a link to a short video - first section is playing the MacGuffin sound, the second is Meow (for comparison) - as you should be able to hear, the timbre of the McGuffin sound varies noticeably.

I've recently got a Sylphyo and have started exploring the built-in sounds.
I've noticed that the MacGuffin sound seems to change if I pause playing for a couple of seconds - it seems to have three variations that it cycles through. I'm definitely not touching the slider or moving the Sylphyo. It behaves exactly the same whether I'm using the internal sounds or the Link. As far as I can tell, it's only MacGuffin that behaves like this. Is this expected behavior?
Thanks!