Tube sound is not about warmth. It's about correct presentation.

Not here to disparage the SS camp,  perhaps our ears and perceptions allow us different avenues to the gratification  of well produced musical reproduction. The Bob Carver interview was enlightening. Never knew of his depth of knowledge as to the auditory process and ability to create amplification that our ears would find appealing. 

Well, there’s Bob Carver’s take, here’s Nelson Pass’ thoughts on the topic (and somewhere here, or another forum, someone shared the actual schematic for the project should someone feel like building a do-it-yourself distortion unit to a SS amp):

https://www.stereophile.com/content/gramophone-dreams-26-nelson-pass-harmonic-distortion

I don't pretend to know anything anymore.... BUT I have heard great sounding SS amps and horrible sounding Tube amps.  So many other things to consider (source, speakers, room, desired tone, genre of music etc.).  There doesn't always have to be a "one or the other".  Keep in mind, the quest for "live" music feel is chasing tone.  All PA systems are SS reproducing "some" tone amplifiers (guitar,bass,keys etc") and presented on loudspeakers.  Of course if you are chasing the sound of an acoustic guitar, horns or vocals that are standing in your living room, that is another desire.  
 

Like I said, I don't pretend to know anything anymore.  But I know what I like. 😁✌🏻

I’ve had mostly good tube equipment over many years w/ some good solid state mixed in between & what I’ve noticed generally is that tube electronics do a better job of giving each instrument or vocal more space & air around it creating a better 3 dimensional illusion. With tubed equipment, The frequency extremes probably aren’t as extended, dynamics may not be as good ( although easily ameliorated) w/ an efficient speaker), tubes die & can be noisy, tubes get hot etc but w/ the right system, generally sound to me closer to live music & are more enjoyable.  

Besides Carver's work, also read David Manly and how increasing the grid isolation resister can make a tube sound more solid state.  

I think Benchmark might disagree with SS "missing" something. :)

Now as far as that "metallic" sound, I did find this as one of my easy showroom "NOs" when auditioning amps. A great test is a good classical guitar recording and if the bass strings sound metallic.  Very clear on some Julian Bream.  A Vocal like Joan Baez can show it up.   My MOSFET passed. Modified Hafler and B&K passed. Atoll and Hegel integrated passed. So does my new Rekkr and Vidar.   I thought it was more Bi-polar vs MOSFET, but some bi-polars' sail through too.  Some failing costing well into the ego bragging range so none of that "not expensive enough stuff". A $150 Schiit passes.  Speakers have a bigger influence and for some reason, I have never heard a hard dome I liked.  By measurements, they should be better, but I keep going back to paper woofers and silk domes. 

Chasing "live" is pointless as you are dealing with the last link of the chain and the sources we have are no where near live. No one has ever succeeded in recording a piano half way believable I have found. ( if anyone knows one, let me know)  If not in the source, we are not going to reproduce it.  Pleasurable is a better goal. 

 The closest to "live" I have ever heard was a solo bass being bowed, 2 mics, right into a Revox half-track. Not even any Dolby.  Played back in the same room through some Levenson and first generation B&W 801's.   Close.   The best we can do is hope not to screw up what the recording,  mixing, and mastering engineers did to it.

I was about to try another tube amp. Last time I listened to some and then built a few, my MOSFET was better in all respects. Things progress though. My desk I could easily use a 6 to 10W amp and those are "reachable"   Jumping to 50 or so on my main stereo is out of my price point. Then I got the Rekkr on the desk and darn is it good. 

What each of think is pleasurable varies.  Sound is real, hearing is our brain deciding what we think. It is not objective no matter how fervently some seem to think it is.  It is personal and neither I nor you can tell anyone what they like.