Preamp no longer makes a difference after caps and wire

A lot of people claim that cables take some time to break in. I've been doing this long enough that I don't question these claims; if I were you I wouldn't sell anything until you've had some time on the system. It does not matter if the cables break in or not- it may be you that has to get used to the system sound; but whatever it is it might well be the case that although you can't hear what the preamp is doing now, you may well hear it after a few weeks of playing the system as it is now.
'I always tell people make one change at a time, and then take plenty of time to live with it so you know you did it right (or wrong as the case may be).

@thewatcher101 - The  Pathos Aurium is a headphone amp. I'm not familiar with it, but I looked it up. The only "outputs" it has are for headphones, plus an 1 XLR and 1 RCA "Tape" output. In this unit, I'm not sure what the difference might be for a "tape" output vs a traditional pre-amp output. I'm not sure you are using it as intended and I'm not sure any advice you may get will be valid considering it is not a traditional pre-amp.

Just curious, how do you have this connected to the amp that powers your speakers? What amp are you using?

I guess this brings up the old issue of active pre or passive pre...or no pre! Everyone has a different opinion of course, and many listeners seem to think that the more that you can eliminate form the signal path the better. I have tried nothing as well as passive twice, and for me, I will always use an active pre. Something is just lost without it...body and three dimensionality.

After bypassing the ignition system in the Morris Minor the engine became dead quiet. No grain, no jitter, no dither, no digital glare.

Update, after a few more session of listening with it on and off, the conclusion is still to keep it. When the volume is turned to listening levels. The tubes even though impact no significant sonic signature that I can pin point, but the higher sense of realism it imparts. Usually with gear, you can tell  what it is doing, but with this preamp and the tubes I am using, the changes are so subtle but significant. By trying to identify what it was doing, I kinda of lost the point to just feeling how my system was delivering music. Very interesting