I should have made that clearer - I’ve ordered a Zyxel, to see if the internals are the same as the internals of the Silent Angel and English Electric.
I’ve seen photos of a modded Zyxel GS108B V3:
And here’s a screen shot from Hans Beekhuyzen’s “review”:
Those switches share the same board. The Silent Angel has a 0.1ppm 25MHz TCXO on a separate board in place of the stock XO. You can buy one on eBay for about £20. Not that changing the clock makes any difference to how a network switch performs…
The Zyxel costs £20, The Silent Angel costs £399.
Where does the other £359 come from?