Is it still worth buying a Lumin x1 in 2023?

Unfortunately, it's going to be a little hard to answer all your questions as I doubt there many people that have heard a D2 with your listed dac options versus an X1.  

Will the X1 eventually become obsolete, sure....but so will every other streamer that's out there currently. Even at 5+ years of age, the X1 is still one of the best streamers on the market (Imho).  We really are not seeing a ton of new streaming features in the near future that would lead to short term obsolescence.  

I personally lean towards one-box streamers as my preference, but if you really would like to have a separate dac, you may actually want to consider swapping your D2 for a U2/U2 Mini in combo with one of the dacs you are considering.  

Goldprintaudio, is that not throwing money away? Why dont use the d2? the dac is the one who must do the job.

Wow, you bet you’ll get a major upgrade! This type of source component in this day and age is pretty much the center of your audio system that can handle about 90% to 100% of your music needs, absent a turntable. The x1 is top notch in every way. Lumin was on my short list when I wanted to purchase a streamer to handle the music on my NAS, quobuz etc. I eventually went with an Esoteric for may reasons but most importantly it allowed me to use dac with other components. That’s my story but to address your question, the x1 would be a major upgrade. 

The best answer to more of everything is a better room.

If you want the thrill of change and shoppin for it, maybe you want to get an additional amp or speakera you can rotate in?

In trouble shooting a problem one needs to start from the very first link in the chain. For streaming it is the digital signal that eventually is the output of your streamer. Digital streaming is full of noise that is getting pulled into the path from everywhere. It’s a noise you don’t notice until it’s gone. Start with router upgrade power supply, then if you hardwire to streamer bring in fiber media converters or if wireless use mesh system. Use lps to power fmc keeping dirty and clean side separated. This can all be done for $500. Then if still not happy move to the next link but now you know the first link of the chain is not the issue. If your first link is dirty so will everything after it be. Streaming is not simple but when implemented right it can be magic. Enjoy the music.