Never thought I would be alive to see this day...
- People understand that DAC is present in everything with analogue output
- The first guy who replies understands the scientific method
Touching moments aside, it should be possible to differentiate between onboard and a better DAC, but usually not in the way you think it is.
The issue with ABX is that the tester usually gets engrossed trying to figure out the differences that he/she/apache focuses on the areas with minimal differences but misses out on where the differences exist. So tip: Try to relax as much and use as per normal as possible, and see which gives your ears less pain. It results in some amount of placebo, but is better than trying to focus on listening, which generates way more placebo by confirmation bias.
The key difference between better and worse equipment is their compatibility. Bad equipment can for example hiss or pick up / generate random noise. Or high output impedance. Or insufficient current/voltage. Or frequency response. These can show up as audible differences and unquestionably show up as measurable differences. But if you can operate it at a point the issues don't show up, then it still becomes as said: unless you can tell them apart in an ABX. Measurements help to give us more precision/confidence in our conclusion, but the end question of "does it matter" is always up for debate.