Best amp for natural timbre of unamplified acoustic instruments & vocals w/ Revel F32?

Maple, it is great advise to sell. We all have subjective likes and dislikes. The speaker sounds this way to the poster and to another it would be heaven. Subjective. He should consider selling as they don't fit his particular taste. 

If those speakers sound that way, IMO, it's because they are just not working in your room.  In a typical domestic environment, It has always been my experience that some speakers work and some don't and it's trial and error until you find something you like.  That said, I would buy an integrated with tone controls like the Mac or perhaps some others.  This will allow you to better contour the sound to your liking.  Good luck. 

There is another thread on the harshness of these speakers. For the music you like look at Harbeth or Spendor and tubes.

Based on the information provided my instinct would normally be to advocate selling the speakers.  Assuming, of course, that your assessment of their sonics reflects adequate break-in, experimentation with placement and with settings of the controls that are on the speakers, etc.

However I took a look at the manual for the speaker, and I note the following rather unusual statement in the section that lists maximum recommended cable lengths as a function of gauge:

High loop resistances that exceed 0.07 ohms (for each wire run) will cause the filter network to mis-terminate, resulting in considerable degradation of sound quality.

("Filter network" presumably referring to the crossover circuitry).

In its effects on the sonics of the speaker power amp output impedance will essentially add to the loop resistance of the speaker cables.  Based on your previous posts it appears that you have probably been using Manley and/or VTL tube amps with these speakers.  Virtually all tube amps have output impedances that are much higher than 0.07 ohms, while most solid state amps have effective output impedances that are in that vicinity or lower.

So I would not finalize any conclusions about how to proceed without first trying a solid state amp with the speakers.

Good luck.  Regards,
-- Al