No preamp in system

Everything is relative.

@mrdecibel 

Hi!  I hope all is going well with you too.  
To answer your question: Without the preamp most everything sounds very good, but is missing something. That something is the high frequencies and, to an extent, soundstaging.  And, on some things I think it actually sounds a little better that way. With most things though it lacks a certain presence and excitement.

I agree with @ghdprentice that live music should be your benchmark. Acoustic instruments and voices are the touchstone. I don't really compare components to each other but rather listen for how "real" it sounds in my system. A lot of gear can sound impressive but over time seem artificial in some way. 

When I make changes I use music with singers I've heard live. I have an enduring sense of how their voice expressed emotion and I listen for that. 

I do experience getting "used to" a certain sound and liking it, but that's because it corresponds to my expectations for sounding real. If it doesn't sound that way, I don't get used to it, I get annoyed by it. 

Impeccable timing. Had long meant to pull my old Rega Cursa pre out of of the chain - as my Shanling tube power amp has adjustable volume. Mac Air, DDC, I2S to Pegasus to Shanling to MG 1.7s. Finally got to it last night and after a disappointing evening have put it back as it was. What I heard immediately and unmistakingly: the 'sidewise spread' of the sound narrowed entirely between the speakers. I didn't notice anything front to back but in truth the impact of the narrower soundstage was enough that it wasn't even on my radar. Secondly, the detail down to quiet was gone. Actually gone. As best as I can figure - detail was less overall and just highly noticeable when a note or voice was tailing off to silence. The soundfloor was dark and noiseless. Some of my very well recorded/produced pieces still sounded impactful. Sharper even. But no sparkle. Kind of unremarkable. Not what I expected at all. I figured pulling the pre out if anything would allow more detail to come through, esp as the Rega is older and not state of the art by any means. Contrast to how my system sounds with it in...? Well recorded music is simply astonishing. Seal. Rhianna. Adele. Isaak. New Shins. Many others. Average music doesn't get as much play as in comparison sounds 'nice' but not remarkable. Poorly recorded music sound terrible. So my system is clearly rewarding tracks and mixes that are well laid down - to the extremes.

@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.