This is a huge discussion and has been done before in this forum a number of times.
Of course the backdrop of the discussion is the Tannoy Westminister, and generally the Tannoy Prestige line of speakers. There were a few statements regarding the 'very very colored" nature of these speakers - and then a whole discussion ensued on neutral sound, its feasibility in a system and the live unamplified sound as reference.
IMO and experience, no single audio equipment can be perfectly neutral. I firmly believe, there are scientific reasons behind it. Any equipment has passive elements like internal cabling and capacitors, and even stuff like volume pots etc and these necessarily produce some coloration. These act like a medium through which the signal passes and the unavoidable effect of that is scattering of the signal and a necessary consequence of that is that the spectral distribution of the signal changes, something that we call coloring. In simple terms these passive elements act like mild equalizers on the signal.
Now if the above is true, the job of the listener is to pick and choose all components including cables so that the overall result is as close to neutral as possible. Now, about cables, I have have heard the purists say that the cables should be transparent. But I have not been able to understand how that is possible, because a cable, no matter what it is, is not vacuum and is a piece of a conducting material and the signal passing through it is going to experience the material and as a result some of its characteristics would change inevitably.
Now, coming to the Tannoy Prestige line, I have heard a few of them, most recently the Turnberrys with a variety of amplification (Naim, Odyssey, Leben, LM Audio etc). The tonalities are pretty good, that is, the Ali Akbar Khan Sarod does sound like an Ali Akbar Sarod. What color is to a picture, tone is to a sound. And tone is decided by the spectral distribution of all the frequencies of a given piece of sound. Hence, I do not understand in what sense a Tannoy Prestige is "very very colored". What these speakers do is to produce a lot of harmonics that makes the melody tuneful and the sounds extended. Harbeth is another speaker that does this, albeit in a different presentation than Tannoys. All acoustic musical instruments are made with these harmonics in mind, and they all use Helmholtz' theory of resonance. This is the reason why every sitar, sarod, tanpura, violin, piano etc and the Indian drums like tabla, pakhawaj, mridangam etc are tuned every 6 months or so (all Indian drums are tuned to the melody unlike the Western drums) - purpose of the tuning is to ensure that all the important harmonics are there, otherwise the instruments sound unmusical and out of tune.
The usual examples of colored speakers I am aware of are the ones which tries to produce an unnatural plentiful of bass and/or cutting down the highs.
Live unamplified music is rightfully held as a reference for neutral sound - something that the reproduced music should be compared to. The question that has been correctly raised in some form or the other is that how many people have the opportunity of listening to the live unamplified music. True, a very valid concern. But the trick is to listen to a given artiste on many occasions live (amplified), and then listen to the same artiste on many systems. From this one gets a fair idea of the tonality of the artiste's voice or the instrument. Fortunately I have heard quite a number of Indian artiste's live and unamplified in somebody's home or green rooms of auditoriums or in studios (when the recording was being done). I have also been fortunate to be in some of the very famous concert halls in the West and Western music in those halls is largely unamplified. For me, it's very difficult to accept a system or recording, overall effect of which is to make Ali Akbar's sarod sound almost like a guitar. Believe me, I have heard such systems.
But for people who do not have this opportunity, still I'd encourage them to attend as many live performances as possible even though the sound systems in auditoriums in India are mostly unbearable. This will still give an idea of the overall flow of emotion by the artiste through the music and try to reproduce that part at home in his/her system. Listening only to reproduced music at home in your system will never give you the impact a live (even amplified) performance can give.
Regards.