Room is a bonus room with knee walls with carpet and bookshelves everywhere, but not officially treated. I sit near field.
That is great ^^^ .
But as I see it you got great electronic and gear.
So at this point my view is that you are asking how you can spend more money to get a different sound probably not better but just different and maybe hopefully to your more subjective liking. With the gear you happen to have currently.
I see that you are at the point there you will just carry in and out to this room different HW/gear. And the combination of gear will give you a differently frequency response.. And if we looking at it from that point you will use gear as a equalizer and that is a very expensive way to equalize the sound and very cumbersome to do equalize. (But maybe just that is your hobby and keep doing that rest of your life and enjoy. You can also stop reading here.)
Another problem with use gear for equalizing is that they're static. For example if a specific item is good in low level listening senario or something else that you value. But you value other stuff also so you will come to the point that swapping out X component will sacrifice low volume listening experience for something else that you like. In other words hard to keep both things in some situations.
- But if we want to increase sound quality.
- And depending on mood/time on the day still be able to enjoy your system at different volume levels.
- Plus being able to tailor to your own preferencences (!) That can adopt to you change preference over time.
- Plus it will adjust to your specific room, gear and their physical positions.
What is that magical thing that can take you to the next level?
Get a DSP and measuring mic as a preamp (that is the correct position in the system). The analog (TT), digital streaming and optical media.
Then you can integrate your subwoofers perfectly and for your room at your listening position. The same goes for the mains. You for example have four presets on the Mini DSP FLEX (measures as a good) that you can use different volume levels (as a loudness control) and with your preferences.
So better sound quality (indirectly fixing your room issues, that you even don't know probably you have today..) and versatile that do stuff that none if your other HW can do today. That brings added value to your system and you.
But you can use something more automatically calibration as Dirac or you can do it manually and with REW. That has a steeper learning curve but you have time to learn.
(When you have a TT and 2 rels then the DSP can fix issues with rumble (acustic feedback from the bass to the TT depending on tonearm effective mass and the compliance of the cartridge the frequency will vary depending on them.) Implement a high pass filter in the DSP. So you see the DSP has many use cases, but you need to know about them.)