I wish someone would do a board for a 1566.
I made one many years ago and tweaked the values so that I got a nice symmetrical rounded distortion [top and bottom of wave form] from the first stage overdriving the second with an LED distortion indicator - and it's been my goto unit ever since [usually running either an AKG414EB or C12 through it], often before selecting Neumann's through V72's.
It has an RE-115K input transformer and the output is just direct through a cap [no transformer].