This preamp is a great bit of kit, one of the things I have done is upgraded the valve (I’m only using one channel). This wasn't as staright forward as I envisaged.
Firstly the cover needs removing - the little screws are not standard - i found an allen key worked fine
I then observed the valves were held in place by z clips that were afffixed to the PCB by a screw from underneath the printed circuit board..
This meant completley removing the PCB to get to the underneath of the board
Old valve out
New valve in.. (and then from here reassemble in reverse)
