UPGRADE PATH FROM CHORD QUTEST

I own a Qutest and the RP-1, so this is an interesting thread to me. I found the stock J&J tubes to be VERY poor… unresolving, muddy bass etc. I bought 3 sets of NOS tubes. Brimar CV4003, Siemens nickel plates & Tele red tips. All significantly better sound than the stock tubes & each with their own unique sound. Upgraded tubes is my recommendation. 
Also, your Lumin streamer was one of my target streamers & I was talked out of it in an Audiogon forum discussion and went with an Aurender N150. 

To add to my post (no longer editable), while not all of my Qobuz streaming sources sound wonderful, Diana Kroll always does, as do many others (virtually anything 24/192). Very happy.
BTW, the Chord Hugo Master Scaler sounds intriguing. That plus tubes could be your solution & within your budget. But start with tubes IMHO.

When I bought my NOS tubes, I thought I would sell my stock JJ tubes on eBay. They are going for $25 a pair… not worth the effort & demonstrates what people think of them. Food for thought.

When I asked Rogue for their recommend tube upgrade, the RCA clear tops were on their list.
Another data point, I brought my RP-1 based upon another Audiogon recommendation. He stated: “So after switching out the two stock J&J tubes that the RP-1 comes with (to Mullards) I was completely sold on the RP-1 and it is a keeper.”

Just out of curiosity, what is your reluctance to change out your tubes? I guarantee you will significantly improve your sound for a (relatively) small investment.

One more pitch on tubes. Eliminating the J&J’s was the most sonically positive impact I ever made to my system. Much more than electronics, phono cartridge/stage, DAC, steamer, cables, power cords etc. Each of my new tube sets provide an excellent, strong & unique sonic signature. 

As others have said, your planned DAC change may improve your sonics, but with diminishing returns, the improvements will more than likely be subtle & not address your issue.

The J&J’s are like bottom of the line Shiit. They may be the best $12.50 tubes that money can buy, but IMHO do not belong in any quality system.