Where to insert tubes while running a Luxman SS integrated

Thanks all for the insight.  Given that I’d like to run with the Luxman, get a somewhat warmer sound through new speakers (the Tannoy Legacy from what I can tell should be a bit warmer than the R3s while maintaining a lot of the imaging/soundstaging of the R3s), and that changing the pre might not be such a great idea, I think moving to tube dacs and phono preamps is my next step here.  The Lab12 Dac 1 Reference recommended by @auroravengeance seems compelling on the digital side.  Does anyone have thoughts on how such tube dacs compare to the popular R2R dacs from Denafrips and Gustard for instance? 

maybe a tube buffer in the pre-out/amp-in loop if connection avail.  

I don’t subscribe to the notion that you can sprinkle in some tube flavoring and get a substantial improvement in sound.  The fundamental electrical component that matters most, and will determine the basic kind of sound one will have is the power amplifier.  Given the wide difference in the sound of different tube amplifiers, and given that compatibility of tube amps with particular speakers is critical, it is imperative that someone investigating tube gear experience different amp/speaker combinations.  

OP, if you are poised to purchase Tannoy’s in near future, I would not spend a dime on any other component now. It’s important to get the synergy right between your Integrated and Speakers. Adding a DAC or phono is not going to mask the issues between Luxman and R3S. I have been down this road where I kept on upgrading upstream components instead of addressing the real problem. Having heard Luxman Integrated, I do not believe Luxman is a right match for your R3S or Tannoy’s. 

If you still feel the need to insert tubes the Luxman integrated is probably not the one for you.