Preamp no longer makes a difference after caps and wire

I just wanted to check if anyone else had this experience. My tube preamp use to be pretty important at removing the harshness from my dac. Since I’ve upgraded the wired in my whole system and caps on my speaker they gave the system a tube like quality. I’ve been skipping the tube in the preamp and the difference in sound is almost minimal. I think I would have a hard time a/b the difference. 
What do you mean skipping the tube? Do you mean it's still there but doesn't make a difference sonically?
I can turn the preamp off, and it just bypasses it. 

Even when I turn it on the difference are extremely minor to warrant keeping it in the system generating heat. 
What is meant by 'I’ve upgraded the wired in my whole system'?
Did you replace all the wire in your power amplifier, DAC and speakers??
Or just the interconnect cables?