There is no Mk2 for the EL84 PCB. Version 1.6 is the latest. Mk 2 is only for EL34.Hi i have a set Mk2
John65b, Prasi is considering a new GB with updates - see here: https://www.diyaudio.com/community/threads/gb-for-baby-huey-pcb.312869/page-70#post-6920890