The Consonance Billie 300B SET amplifier kit was originally available from Diy HiFi Supply. This was a dual mono 300B single ended tube power amplifer with many upgrades and possibilities.
I upgraded this unit over a period of 5 years to incorporate the newer Ladyday 300B features such as the WE91 power supply, Ultrapath caps, MU driver stage and grid chokes. Below are the original various pdf files such as build reviews, tweaks and upgrades.
** I have included the circuits which would allow you to build this amp from scratch build as the kit is no longer available **