So where should the tubes be?

Isolid state has evolved a lot ,fet, mosfets have several characteristics 
like tubes no more bright sounding ,thst being said a tube preamp is my favorite 
spot , too much tubes a bit too soft on leading edge . I prefer SS the dynamics control and current delivery have their advantages especially to control 
In Bass  drivers . I have used tubes for 40 years , I no longer feel tubes are necessary for detailed Rich , natural sounding music , but in the preamp section 
I feel the best position with a Solid State power amp .
my New Coda SCIB integrated with VH Audio Odam capacitors in the class A 
preamp section ,it sounds very natural sounding ,with the Bricasti dac-Streamer front end a very balanced sounding system.Everyone has their own  preferences .

Started with a Yamaha A-S501 solid state integrated amp. Good sound.
Put a Xiangsheng 728A tube preamp in front of it. It was a firm change from the good SS setup to a setup that had musicality, if that means anything.
Dropped both and went to a Quicksilver Audio Integrated tube amplifier. I cannot imagine more musical reproduction. I can imagine more of a you-are-there sound, more separation of instruments (as if I ever cared about that in a club or concert hall), but not more musicality. And then I'd need a new listening room and new speakers, too (Focal Aria 906's throughout the above).

I like tubes everywhere 19 total in my system, Dac, preamp, and amp. To me the big aha moment was my first tubed preamp so I would start there if I was dipping a toe into tubes for the very first time.

So there you go. Use tubes wherever you want music.

some of your audio idols like Fremer and Lavigne love their SS amps and believe they actually produce music.  Why so polarizing and disenfranchising of so many people at every opportunity? (rhetorical question)

Three Easy….he doesn’t know a FET is solid state