The C30s, like the AC30 do not need a standby switch (because of a slow startup voltage ramp).
Described in detail here:
http://www.peavey.com/support/technotes/hartley/chapter_6.pdf
The pop is a different issue that a competent amp tech should be able to sort out (big ass cap across the power switch?).
No JJ are not stock, IIRC, the stock valves are Sovtek.