Tried tubes and LOVED it, now what?

First off congrats on finding the light......I'm not a fan of KT88's,great bass but the mids are no where near as lit up as EL34...You could:
Consolidate all speakers to 1 pair of Hi Eff.& go 300B SET or something S.E.Triode Strapped or 300B Push Pull...
 Consolidate all speakers to 1 REALLY good pair & try some tube rolling,especially the small signal tubes along with some cable rolling...
 Stick with what you have & try tube/cable rolling...
Is the room treated?You will be surprised how much an untreated room affects the tone...Good luck...

nasaman I forgot about what is involved in biasing that amp...Start rolling with the small signal tubes,they do not affect bias voltage...