New tubes for SFL-1 / SFS40

I'm thinking of replacing some tubes for both my amp / preamp. Currently, the system doesn't sound "tubey."
I heard the nature of SFL-1 isn't very tubey...but I am
hoping that replacing some tubes on both pre/poweramp will
give me the "tubey" sound that I'm looking for.
Please give me some suggestions on the tubes.

Thank you very much!

Wow...this is getting interesting.

Dekay & Fpeel, thanks for the link.

Dtails, where can I find more information on caps? DIY? I'll do some research on AA. Thanks alot. This is fun.
No problem, do a search on 'paper and oil caps' should bring up places like The Parts Connexion, Audio Asylum. The Parts Connexion has them for sure
Let the fun begin!
I just purchased a Zero Autoformer. My system sounds more dynamic (much better bass) and the high is more focus.
Because of the extended mid-bass, my system sounds more warmth overall.
I just purchased 4 6dj8 Globe Amperex from Ebay.
As soon as I get them installed, I will give you an update.
But the new Zero really helps my system.

My system doesn't sound dry and bright like before.