Perhaps despite popular opinion, doing a "sort of" objective test is useless. Our brains are wired to unconsciously influence our subjective experiences and there's nothing we can do about it and it doesn't matter how much experience we have or how smart we think we are. Therefore we need to be very careful to eliminate
everything except what we are actually hearing with our ears (not what we think we are hearing).
Just eliminating some things is a waste of time as it produces unreliable results, so you either do it right or don't bother unless you're making a subjective evaluation to begin with - i.e. "Which mic do I prefer?" (a preference doesn't matter too much if it's influenced by expectation bias), not "Can I hear a difference?" (an objective fact that requires very careful testing to eliminate all subjective bias because otherwise it isn't objective).
Proper objective comparison
requires:
Identical source material.
Careful level matching to within ~.1dB SPL.
Double blind or completely blind switching.
No switching artifacts when switching sources.
Truly random switching.
Reasonable source material and listening environment/levels.
Statistically significant differences to minimize the possibility of guessing.
If you can't achieve all of these things, you're fooling yourself if you think you're getting more objective results. Science doesn't require all these careful controls just for jollies - they're required because otherwise the results are simply unreliable. It's actually relatively easy when comparing digital audio files/formats - just get and learn to use some ABX SW, but unfortunately it's often very difficult when trying to compare hardware.
You might find it easier to measure the differences using test tones or something like RMAA to see exactly what the differences are:
http://audio.rightmark.org/products/rmaa.shtml EDIT: The short answer is either do it right or don't bother. Anything else doesn't make any sense if you actually want to learn anything about reality.