Anyone recommend a neutral tube amp?

Based on my experience, I would recommend you audition Rogue Audio's Tempest II. I went from Simaudio's i-3 to Rogue separates, the Perseus and the Stereo 90.

I found the Rogue combo added more texture and dimension to the music while being "more neutral" than the very few other tube amplifiers I listened to in the <$1500 dollar range (used).

Besides few other choices that have been already mentioned, I would like to throw -in just one more brand in this mix-up. My favorite amp (yes, I know - I am bias, on that matter) Consonance Cyber 800. It is a 78wpc El34 base monoblock design within reach of most audiophiles.
It is not the best amp out there.........but it is good enough for me. Right now, I have placed it in the hands of a person that will perform some mods on it to get the most out of it...........will see what will that bring to the table and how it will affect its performance .
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I would just like to add that as good as Cybers are there are not the last word in transparency and it may luck some body on string instruments. However It could be the limitation of my speakers. At this moment I am not a 100% sure. I am hoping that treating the input stage, some silver wiring and addressing few other areas where improvement is possible will answer my question.

FWIW the idea that tubes color the sound has the same merit as the idea that transistors color the sound. What colors the sound is anything to do with audio reproduction- IOW it is not a tube/transistor thing...

Ralph, I did not wish to imply that tubes add a coloration to the sound. What I should have said is, that tube rolling will INFLUENCE the rendition of music of a given component. When I wrote my post, I forgot for this moment, that "colour" is detrimental to the concept of "neutrality", which to my mind is a very subjective and unclear concept anyway, as any practicing musician knows, who can voice or tune his instrument in many respects to best fit the character of a given piece of music, just as a designer will voice his product to what he feels fits his concept of musicality best.
And - as you say- of course this is certainly not a tube/transistor thing. I never meant to imply that.
Cheers,

Hi Detlof, got it!

I play in a couple of bands and I know what you mean there. But as a designer, I do exactly the opposite of what I do in the band. IOW, I try to make the equipment do as little messing with the signal as possible.