I promised some thoughts on R3pro vs R3Pro Saber some pages back - Here is the sound notes from my upcoming review.
Determining a DAPs sound quality is always tough in that so many other things play a role in what you hear. Source material, headphones, and even accessories can alter results. For this reason I used tracks, headphones, earphones and tips I am intimately familiar with so as not to attribute qualities of any of those to the DAP. The Saber has good linearity throughout with very little coloration added. The low end has good texture and weight when paired with headphones within its abilities but did struggle with the He6. Conversely, it worked well with the 600Ω Beyers so it struggled more with delivering enough power for He6 than with fighting high impedance ratings. The bass is not emphasized, but has good rumble and slam when called upon.
Mids are slightly dry compared to the R3pro (CL) but have a bit more detail and are a bit more realistic in timbre which is particularly evident when listening to strings. I listen to a lot of string quartet and orchestral works so this was a plus for the Saber. Vocals have good presence and are well articulated as well. Most headphones are voiced to push vocals slightly forward so it was nice to see a dap that didn't double down on this by adding an additional push. Guitar growl is well reproduced as well so this dap was equally at home with Yngwie and Mozart.
The top end shows off the full resolving power of the ESS chipset and is where to my ear the biggest departure is from the CL version. The R3pro CL was a bit smoothed over where as the Saber is more aggressive and a bit more realistic. The CL version tended to smooth over tracks that were by nature a bit rough and strident where as the Saber reproduces them in all their glory. For those who want something that always sounds good, the CL version may be a better choice, for those that want an accurate representation of the track, the Saber does a better job of it. Cymbals are sharp wtihout becoming metallic, snare rattle is realistic, and roll-off is somewhere above the headphones and earphones I was using so didn't limit air or sparkle.
The soundstage on the saber feels a bit deeper than that of the original CL with good dimensionality and some 3d feel. Instrument separation is improved over the CL version due to the slightly more aggressive nature of the ESS. Imaging is good on both and honestly not notably different between versions in my listening.