DAC diminishing returns

The RME is a good transparent DAC. Looking at OP's gear, I don't think he is interested in neutrality. 

 Currently, I’m using a Schiit Bifrost Multibit DAC.  It’s connected to my Naim Nait 5Si and that drives Zu Omen ii speakers.

DACs and amps are about flavor....colorations. I personally enjoy them. Tube amps, tube DACs, R2R...good flavors for me. Give me the second harmonic, give me a slow filter, NOS...I like colorations that make the experience feel more real.  

If you want ultimate transparency then you can buy from Benchmark or even cheaper with something like Topping D90. Have it as the artists and sound engineers intended.

Almost all of us have issues with our rooms. Seeing a measurement of one's room is a gut check. If we put fully faithful equipment and speakers in our rooms, it will put a microscope on the flaws.

So what do most of us do? We buy speakers and equipment that flatters the sound instead of examining it. R2R is a good example. It is easier and more relaxing to listen to for music.  

@jjss49 credibility comes from the wife noticing all the way from the next room.

@mayoradamwest  transparent DACs are becoming a dime a dozen. This is easily measured. Transparent DACs are also no fun and that is why we have tube DACs, R2R and options such as NOS and slow filters. 

DACs are fascinating.  All DACs present you with a tradeoff between detail and soundstage.  If you are looking for fine inner detail, great separation of strings, etc... be prepared to compromise in terms of soundstage.  If your priority is soundstage, be willing to compromise in terms of absolute detail.  

Couldn't agree more. IMO the soundstage is from the 2nd order harmonic distortion.

Same with amps. The Benchmark ABH2 and DAC3 won't give you soundstage but they will give you very high detail.

IMO, what is better is what our system needs to create balance with our preferences. Some call that synergy.

Pro Audio folks poke fun at us, but our goals are just different. Some AV folks also laugh at us, but trying to make music sound believable with only two channels ain't easy. ;-)  

IMHO there are likely 10 other things in your system that need far more attention. I have heard DACs with intentional sound differences using tubes, and I have heard DACs that allow you to change the filter settings that causes an apparently audible difference which you may or may not like. 

Changing filter settings can definitely be noticeable. I believe it is done through phase shifting but I could be wrong. But yes, it is technically a "HiFi effect" or coloration. 

I also agree that it can be very difficult to tell differences between very well measured Delta Sigma DACs. Good luck finding audible differences between a Benchmark DAC3 and Topping D90SE. 

Some people say that DACs are a solved problem. This is true only if you believe the goal is faithful reproduction of the original signal. Personally, that is not my goal and that is why I am a member of Club R2R ;-) 

Many dacs don't have any means of volume control, others strip bits. In order  extracting maximum potential from these dacs requires some form of volume control, the quality of that volume control has major bearing on sound quality of that dac. 

This is true if your goal is to get the music as close to the original recording as possible. The Benchmark DAC3 paired with the ABH2 power amp will get you state of the art transparency for $5000. 

However, many of us would be in for a rude awakening with that level of transparency in our systems. Our tube preamps and R2R DACs add flavor or color to the sound...giving us a deeper and wider soundstage, additional layering, and weight to the sound...the perception of 3D sound.