Best Loudspeakers for Rich Timbre?

My speakers.










That was a jest.

Speakers don't do math. Nor are they polymaths given the numbers of instruments, materials, musicians, tuning, styles, etc. etc. in existence.

Yes it's fair to say that all speakers must either be adding or subtracting to timbre

Timbre is the human (expert) perception of the sound of a note made by a specific (tuned) instrument, brought into existence by a musician.

Instrument. Musician. Human Perception of Sound. Note: No speakers involved.

From this point on, there is a very long chain which attempts to provide a 'facsimile' of that note. What you are hearing in your listening chair has to do with that entire chain.

Rectilinear III's with their 5 drivers and wide baffles have a lot of "presence"! I have both the Highboys and the Lowboys! 

Hi, there may not be a problem with your speakers or system.  Jim Smith's book points out that bringing the speakers closer together riches the timbre.  I find tweeter to tweeter should be inside 5 feet with speakers towed straight at you and exactly the same distance from your sitting position/ears..  Benefits include good focus with no smearing and a better sense of dynamic contrast between instruments and acoustical space.  Of course multi-miked pop and rock records have little or no ambiance, but at least the timbre is better.  I assume you attend live un-amplified concerts.

Many actually, but what comes to mind are Tannoy, Harbeth, ESL in general, and I must state as always the XTZ Master M2... a jewel of a speaker given the right amps