Hello,
That is really great you are happy with your system. One thing I have noticed is new tweeks come about from time to time. If you don’t want to try new stuff then by all means just listen. I watched a YouTube video about cleaning the air in your listening room with a HEPA filter system. Very interesting. I am sure 10-15 years ago a few of us were happy with the system. Then the new cool stuff comes out. If you get the chance I would try a preamp. Even if it is passive. I know some of these new DACs have killer volume control like Playback Design or Lumin. When you have a nice preamp it becomes the soul of your system. ISO acoustics for your speakers or adding a sub or three. If you are done for now you are very fortunate.
For the Hepa filter I am going to tape a 20”x20” Hepa filter from Home Depot to a cheep box fan since you do not run it while listening to music. It’s not a permanent solution but it will provide the same results as long as the filter goes down to 3 microns. I hope it works. I love cheep tweaks.