@OP. The best test is when you reinstall your preamp. Perhaps your preamp has been limiting the sound of your system so the system actually does sound better without it. Or when you reinstall the preamp, maybe the sound will be better than with no preamp.
No preamp in system
I want to point out how the perception of our equipment changes over time. I’m getting so use to the sound of my system without a preamp (which is out for repair) to the point that I’m accepting it as good sound. It reveals something about our hobby. When we get new equipment we often say “let it break in.” And lo and behold, it sounds much better over time. Is it that were really fooling ourselves, and that it’s simply a matter of us getting use to it?
Just food for thought.