in order to do a definitive test of a speaker's ability to reproduce timbre accurately, it is necessary to record an instrument in one's living room and compare the recording to a musician's presentation of the same music.
of course one will need a musician who is willing to particpate in this experiment as well as a way to method for recording, such as an open reel tape deck, a dat, or a cd recorder. hopefully, the quality of the recording is sufficient to make a meaningful comparison.
Not completely necessary....you could simply buy the equipment used to impress musicians in the world's top studios...the main monitors...there are literally at least a half dozen highly respected designs and all of them have excellent timbre and play at realistic sound levels of live music. You have to count on the fact that top artists and top conductors are auditioning play back of THEIR music on these same speakers which you can easily acquire...what more checks and controls do you want?
Of course your room will always be a major factor....no doubt that studios spend a lot on room designs and acoustic treatment. I figure it would be highly wasteful to get such quality speakers and then not treat a room at least modestly even though many of us have to respect domestic dual purpose requirements.
Good Luck! Try trusting the artists and musicians and sound engineers themselves...pick an artist or a record label with outsanding audiophile quality productions and then find out what they gear they are using...for example Bob Katz of Chesky uses Lipinski monitors....