What is wrong with my system?

There is a simple solution.    

Just wait until you are in your late 60's and you won't be able to hear anything above 12khz anyway.    

Problem solved.

Get a turntable and a few records and I am sure it will sound better.

Looks like your speakers go down to 34hz....I would add a subwoofer...then play with placement...then run REW for the final touch....IMO...

Several writers have suggested substituting a vacuum tube preamp.  I would recommend a device based on the 6SN7 such as one of the superb Cary units or Roy Mottram’s Vacuum Tube Audio SP14, which is an excellent bargain.

Some good suggestions and some rather radical suggestions as well.

Do your due diligence and really work on speaker placement.  Mark the location of the speakers before you begin.  You may wish to consult the Cardas Room Setup & Speaker Placement Guide:  Cardas Room Setup Guide
I believe that you will reap great benefits and then tackle some room treatments if need be.  At that point which I hope is successful then you may consider a singular change to dramatically change your sound.
Most folks are suggesting to ditch your SS Preamp and go to a Valve Preamp.  Preamps are a very difficult and critical component to get really right.  Lots of mediocre and very bad preamps to choose from.  Audible Illusions makes sonically good preamps with one caveat.  They don't drive very long interconnects (at least that's what I've read).  The M3B has twin triodes and is a full function pre and has an option for phono boards for low output MC.  It was my second choice but I opted for the Sutherland Engineering N1.   
Take it one step at a time.
Best