Lumin D2 upgrade with external DAC?


A similar question was asked on this forum in August 2018, but the OPs question was never really answered. Also, i believe stand alone DACs have improved their performance/$$ in the past 2 years. 
My main listening is (Tidal & Roon) done using the Lumin D2/Roon Nucleus feeding a Primaluna Dialogue HP integrated, into Goldenear Triton 3 speakers. I’m looking at two areas to upgrade this system. One is to replace the Goldenears with TBD as i’m still auditioning various full range floor-standers (Marten, Magico, Joseph Audio, Revel, GE Triton Ref0.   The other area to improve is the digital source which is what id like to draw on this forums expertise for information or advice. 
A couple of insights into my listening aspects that may affect your responses are:
  1. I mostly listen to acoustic jazz because of the organic nature of the music/sound.   2. Due to long term high frequency tinnitus, i am no longer able to hear above ~ 9,500 Hz. I do feel like i still have pretty good & discerning hearing below the 9,500 Hz barrier. 
So here’s my question; can I expect  to get a noticeable i.e. not insignificant improvement in musicality (in my hearing range) by adding an outboard DAC like the RME ADI-2 DAC, TUBADOUR III Non Oversampling Tube DAC, or similarly priced standalone DAC?  This is not an either/or question, I’m going to upgrade, that part is taking years to determine what speaker sounds best to me. I live in Huntsville Alabama which despite all the high tech companies, is an audiophile wasteland. I had to travel the Oklahoma City to hear the Martens, Atlanta to hear the Magico, Nashville to hear Revel and Goldenear, and am currently planning a 7 hour drive, each way, to North Carolina to the nearest Joseph Audio dealer. 
Thank you in advance for your thoughts on whether spending less than $2,000 on a standalone DAC makes sense or is just an audio fool on a fool’s errand. 
ezstreams
I am a very satisfied T2 user. I also have a prima Luna integrated. Have you considered selling the D2 and then putting that money towards a T2? It is a big step up in sound quality
Thank you tuberist. I have thought of that option too but is another ~ $1,500 above what i was looking to spend. I will keep it as a plan B though.