Falling out of love with tubes


I’ve owned an EICO ST-70 for eight years.  It’s modified and upgraded to the max, but with budget tubes. 

I just got got a Conrad Johnson SA-250 for a steal.  I plugged it in and it has blown my mind.  I feel like I’m hearing my music for the first time! So much detail I never noticed before!

I’m selling the EICO and will use the money for a preamp.   The SA-250 amp sounds kind of sterile/clinical to me.  Very unforgiving of a mediocre recording.

***Will using a preamp instead of going direct from my computer or tape sweeten the sound, even if it’s the solid state CJ Sc26 preamp?

***Will I lose the detail I hear if I get an older CJ tube pre in my price range? (Pv-10al) 

I’m listening to Silverline Prelude tower speakers, anticables level 2 speaker wires, anticables level 1 interconnects, and Denon dvd-2200 for CD, parasound zphono USB for my Supex SDX-1000  mc cartridge.  (Haven’t tried anything but phone, computer and cassette since I don’t have a preamp) 

Thanks in advance for your input. 
audibleaudio
Even Paul McGowen thinks preamps are necessary:
https://www.youtube.com/watch?v=Dh27E7YKN9s

And, I if I were you, I'd consider one of the Atma preamps.
B
“...a tube preamp will give me back those rich odd-order harmonics I have a taste for...”
I think you meant even order harmonics and the CJ PV10AL delivers plenty of them, maybe a tad too much depending on your taste. Real juicy midrange if that's what are after but a bit rounded off on top.
Last night I tried a Cary CAD-5500 premamp between my Audio Refinement separates (Pre5 preamp and Multi5 amp) in an attempt to get some tube harmonics introduced in the signal chain. Didn’t last an hour as it dulled my dynamics and musicality.

Rest of system details on my system page.
There are lots of preamp s I have Custom built preamps far better then commercial  where 70% of your hard earned money goes into the unit s parts . Did you know less then 25% on average hoes
Into any commercial product the rest ovrrhead,and 40-50% 
Dealer markup. I owned a store  and know about nodding,
And quality.  Used you can find good equipment 
But first you want very good quality coupling capacitors installed 
Very important  under 10 years old , any older capacitors of thst era start drying out on lesser brands,  if remote control most use alps volume which you loose a lot of inner detail .look for resistor based , or processor . There are a ton of variables. Being in audio since the mid 70s ,I have a college education .