Have you tried matching a stereo to your hearing?

I think that three different things are being talked about here, which are not being adequately distinguished:

1)Adjusting the system to compensate for the Fletcher-Munson Effect. This is what I interpreted the original question as referring to.

2)Adjusting the system to compensate for particular hearing deficiencies an individual may have.

3)Adjusting the system to compensate for deficiencies in the recording.

Regarding item (1), in general you don't want to do that. If the goal is for the system to recreate a live performance as closely as possible, and assuming that the listener has reasonably normal hearing, and assuming the system is playing at volume levels close to those of the live performance (as perceived at the listening position in both cases), any compensation for high or low frequency rolloff that our hearing will have at that volume level will cause the reproduced sound to be perceived differently than the live sound.

On the other hand, if circumstances force one to listen at much lower than real-life volumes, then perhaps some electronic compensation for the Fletcher-Munson Effect can be appropriate, if the particular circuit implementation is of sufficient quality to not do more harm than good.

Regarding (2), electronic compensation would certainly seem to be appropriate for some listeners, who may have significant hearing issues.

Regarding (3), there is no one right answer, and in previous threads lots of diverse opinions have been expressed about this. It comes down to individual preferences, and the kind of material that is listened to.

Best regards,
-- Al

Mceljo, your option (4) is expressed a little differently than what I was addressing as option (1), but I think that similar reasoning applies in both cases.

My thought was essentially that an electronic correction for the response curves of a particular listener will cause him or her to perceive an accurate reproduction of an original performance differently than that same listener would have perceived the original performance. Which would seem to be contrary to what we try to accomplish in striving for high quality music reproduction.

Of course, use of electronic equalization, digital room correction, etc., may be called for in many cases in order to make the reproduced sound as neutral and accurate as possible, or as subjectively pleasing as possible to the
particular listener, or to compensate for particular hearing deficiences, or to compensate for having to listen at low volume levels. But those are separate issues.

Some of the others who responded above appear to me to have expressed essentially the same thought.

You raise an interesting question, though.

Best regards,
-- Al