If my Rocksmith 2014 is not having any identifiable tone changes, while playing on my PC, is my cable screwed?

  It was working fine, now there is no difference between any of the different tone, i.e everything sounds clean.

  I have a Gibson with passive pickups, a Schecter with active ones ( no, the 9 volt is good)?  It's the same way with both guitars

If my Rocksmith 2014 is not having any identifiable tone changes, while playing on my PC, is my cable screwed?

  It was working fine, now there is no difference between any of the different tone, i.e everything sounds clean.

  I have a Gibson with passive pickups, a Schecter with active ones ( no, the 9 volt is good)?  It's the same way with both guitars

That's one of the bugs RS 2014 has when the song you play doesn't have a tone assigned, also happens sometimes in random moments, so keep trying that i'm sure your cable is fine 

If this happens just restart the game, thats what I do

I doubt that it is the cable.

 

as per above comments, just restart the game.

 

there are lots of CDLC that have minor issues that effect the game adversely like you have described.

I have the problem at least once every time I play, I know it is a couple of CDLC with problems but have not identified which ones (one is a REM song). either way they are CDLC's which I play regularly so I am happy to have to restart every once and a while rather than delete and not play those songs.

 

once I figure out which CDLC they are I plan to play them at the end of my plays through.

Older customs that were packed with an older version of the Toolkit, and don't include a custom tone, cause this to happen.

 

The newer versions of the Toolkit automatically assign a default tone if no custom tone is added to eliminate the problem.  You can repack the custom(s) with the current Toolkit to correct the problem so that it stops happening.