Yeah, that's another step I've considered, checking voltages. I'd have to get a multimeter.

It can be a real PITA to get everything matched for these tests across the DAC and ADC. Getting every test setup properly takes the vast majority of time when measuring, I've found. Depending on which mode I'm testing, setting either of the devices to 100/100 volume in Windows (only method I have for volume/gain control outside of test gain settings in ARTA) creates additional noise or distortion that really isn't going to manifest itself in proper listening conditions. I really doubt either this Creative unit or my NOS1704 DAC have 9% THD, so sometimes you gotta bump that volume slider down on both devices. (For my Auzentech Bravura card in particular, setting Windows volume to 100/100 will actually produce a "hot" signal that causes distortion and clipping on most devices.)

So, I have to find some sort of balance that gives proper levels but without falsely displaying better or worse measurements than in reality. Often times, I will test a large sampling of volume settings across devices that still match up to the same level for measurements in the end, compare results, and tend to go with whatever settings give the most consistent, repeatable, and rational values. Generally I find it works well to match the volume settings on both devices in Windows that give proper levels in measurement software. I know these methods aren't as scientific as they should be, but I do strive for getting the best, most repeatable, most consistent results I can with the methods and technology I'm using.

I think despite all these limitations, there's a lot of good, solid information that can be gathered from these measurements. Plus, I'm always willing to go back and revise my methods and measurements if I learn something new/better. 

xnor or anyone else knowledgeable on the subject, these loopback measurements were done with REW at 48KHz (max I could do). Are any of these tests and results informative, valuable, or valid given the context of DAC measurements? I ran the same tests with the NOS1704 as well (using SB1240 as ADC). Still open to other suggestions to try.

Apologies if the colors make it hard to read...one minute the software used one color scheme in dark mode, and the next it's using another. No idea why.

Would like to post more measurements but I'm not sure they are valid, my unit is measuring weird, I'm sure I borked my ADC after amp testing without zener diodes.

This one is done using periodic sweep, I have repeated numerous test using Steps(I had weird distortion figures -150db THD @20khz. Used the frequency response and voltage functions of my multimeter(Fluke 8060a) to check my DAC outputs for the correct voltages (which showed extended response to 30khz(did not check further)) . Also done a spectrum using the FR function and measurements in RMAA.



Impulse measurements for the lols, mine is the textbook linear phase DAC. Since my ADC is borked(I think) I doubt its valid. (Click below)



Need to take a look at my soundcard settings again but I'm at least sure my DAC has nothing wrong(or I need to get a new DAC/ADC)