How do I internally join inputs in a plexi-style circuit ?

[Iplayloud]

Does the single input split to two 68k resistors, one for each side, or use just one 68k resistor then connected to both 12AX7 halves ?

BTW what is the difference between 68k and 32k input resistors, I think one sounds darker or brighter right ?

Also, in a normal plexi circuit I think going through both 68k in parallel gives a final input resistance of 34k right, then why does the JCM 800 and tons of other amps use 68k rather than 32k ?

For example the Fender Pro Jr has a 10k input resistor, is this to really darken the signal to compensate for a thin sounding amp ?

[Iplayloud]

It's ok, I'll do it like in these schems:
http://www.blueguitar.org/new/schem/...smaker_sch.gif

http://www.blueguitar.org/new/schem/.../plexi_rev.gif