Hi
In January 2000 I bought an Electronic Tonalities Foreplay kit.
It sat in its box until about 2 weeks ago, but now I have a working preamplifier.
I'm pretty sure it's the messiest assembly and soldering job anyone ever did, but it works!
The top side looks just as sketchy as the underside.
Before building it I became charmed by the crazy look of the 7193 tubes and the internet says they sound great so I felt I had to use them.
I ordered 4 tubes and 2 adapters in ebay and was warned by the manufacturer of the adapters that they require 6.3V.
All I did was wire the heater connections of the 2 tube sockets in series and indeed that seems to work.
(In each socket, terminals 4 and 5 are connected and terminal 9 is connected between both sockets. The two 12.6V power cables each go to one of the 4=5 terminals.)
Other than that it's stock, with the anticipation and whispers upgrades.
Right now each tube adapter is sitting on a tower of 2 socket savers to clear the RCA connectors. Once I get some right-angle connectors all I need is a single socket saver on each side to clear the knobs and connectors.