Since you are right that going from a live performance to a recorded performance degrades the performance,even with an excellent recording,it follows that you compare speakers using the same music. At least the degradation will be equal from speakers to speakers.
I stole this idea from an article in a magazine but it makes sense to me:
--Use a recording you've heard over and over.
--Make sure you listen to different speakers at the same amplitude;you might favor the louder speaker otherwise.
--Compare two sets of speakers at a time. Once you've decided between A and B,compare your choice against C,and so on.
Assess according to these four objective factors:
--timbre. Does the orchestrated color of a violin plus a cello sould like the color of a violin plus a cello(for example)?
--imaging. In a three part counterpoint,can you follow the melody,the countermelody,and the third line defining the harmony without the speakers getting in the way?
--dynamic range. Does the distance between a single instrument playing softly and a hundred instruments all playing loudly sould correct.(Even fine speakers will compress this distance a little. Even a good fm broadcast signal compresses dynamic range somewhat.)
--frequency extremes.Do violin half stops and organ pedals sound correct?
I know it's harder than that,but it's a start. Also,it's a personal preference. Maggie 1.6 s don't have the best bass or dynamic range in the room but,for me,the imaging and timbres are more important.
Enjoy the search,when you find something your ears like,get those speakers.