How, briefly stated, do you mean to persuade me that your "subjective impression" is such that the judgments you make because of it (your "subjective preferences") are judgments I should be persuaded are reasonable, well-informed, and worth taking seriously?
Very good question, one that applies just as well to (classical) music reviews, etc, so let me reverse it:
I would be persuaded your judgments are worth taking seriously if I knew you to be consistent, and I knew you to be comparing to a known and shared yardstick (say, live music), and I knew some of your listening traits (are you thorough - are you spontaneous, do you prefer baroque, classic, romantic... combination thereof, do you like to simulate reality in your room or are you after reproducing what's on the medium... etc).
Your judgment will then lead me to extrapolate my own preferences and approximate whether the device (or system, or performance, for that matter) in question is one I might like -- or not... regardless of whether you ultimately liked it; if you are consistent in your judgements and I "know" you, your informed opinion is always valuable whether or not we always agree or disagree.
A brief point on measurements: surely no-one disputes that when it comes to speakers, FR measurements, FFT, etc are useful; these easily correlate with what we actually hear. Regards