Where to insert tubes while running a Luxman SS integrated

I would recommend you go to an audio store, even if travel is required and listen to an Audio Research I/50 or LS28/VSi 70. The contrast with your Luxman will be profound. It will also tell you something about what you should do. If you love the sound… then trade your integrated. If you want to move 10 - 20% towards the ACR sound add a warm tubed preamp, if you want to move another 10% add a tubed DAC. If a movement towards that sound of 35% or s isn’t enough, then swap integrateds.

I recently compared three integrated amps, Luxman, Pass, and Audio Research. The contrast was striking… and pretty stark. The Luxman was detailed and crisp but without musicality and warmth, the Pass was detailed with a much more natural  presentation and palpable rhythm and pace (think foot tapping musicality), and the Audio Research was warm and so emotionally engaging it took my breath away. Be aware… I really love ARC for their sound quality… so it is not surprising my reaction. Some might like the greater slam of the Pass (INT-60). The Luxman looked cool. 
 

I was helping a friend choose… a newbie. While he liked the ARC, I recommended the Pass as it was his first high end purchase… I thought he needed to go through the great slam stage that he could impress his friends with. But he actually thought about it for a couple weeks and bought the LS28 preamp and VSi70. I was shocked and know he will have these for a couple of decades.

Anyway, I think if you listen to what I would consider the possible end point… you could judge how big a move you want to make. 

 A lot of the Luxman magic seems to be in the pre.  I suggest try before you buy.

@wlutke  is absolutely correct, this has been my experience as well.  It's the preamp section that's so incredible in the integrateds. If anything, I'd get outboard amps and keep the pre! :D

If that's not satisfying you, you are going to end up replacing the entire 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.