Phillipe,
That is correct -- install the resistor before doing any more work under the hood. And best to leave the amp off between now and then and it may even be advisable to build a cap discharger as was mentioned earlier.
And also correct that this resistor probably has nothing to do with the other problem, but once it's a bit more safe under there we can get back to figuring that all out.
Thanks also for the info on the usb isolator -- definitely going to check that out.
Where in NJ are you -- grew up there and lived there a good portion of my life.
-- Jim
Jim Rebman -- recovering audiophile
Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).
s.e.x. 2.1 under construction. Want list: Stereomour II
All ICs homemade (speaker and power next)