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!

Looked it up and now understand the 6DJ8s are for the amp, not the pre. My mistake.

A synopsis of the characteristics of a variety of 6DJ8 tubes is located on the Audio Asylum at Maybe that will help narrow down what tube will do the trick.
Hi Sean,
I know that you wanted to change tubes to get the 'tube' sound, but you may also get a lot of that type of sound by changing the coupling caps. Their are 2 pairs of caps to consider in the SFL-1, and a quad set in the SFS-40. Paper and oil caps may be the ticket for you.
Have fun!
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.