For many, it might be hard to tell what this is at a first glance – however, if the myriad of relays clacking won’t draw your attention, the four Nixie digits on the top definitely will!

[Justin Scott]’s tube preamplifier is a great example, with its novel use of a pair of Nixie tubes to indicate the volume to which it has been set. The audio side of the preamp comes courtesy of ...