Upgrading from Thiel 2.7 to Sonus Faber or Focal???

Let me suggest changing the 4 center 12AU7's in your Primaluna preamp.
I would suggest NOS Mullard 12AU7 long plates. They will definitely have an effect on the warmth of your system compared to the stock Primaluna tubes.

Its an inexpensive move before changing speakers that you might like already

Good suggestion rushfan. Are the Mullards overall quite a bit warmer than the stock tubes? Price per pair? I do remember going down the tube swapping fiasco with the PrimaLuna Dialogue Premium integrated I had a few years ago.  Drove me crazy lol. 

Sounds like you'll just have to get the SFs and keep the Thiels.

That's the route I took.
When I auditioned a ton of speakers as possible replacements I'd come back and listen again on the same tracks on my Thiel 2.7s.   This just showed how great the Thiels were.  They are just so even handed and competent from top to bottom, they make most other speakers sound more obviously colored. 

So I saved up longer so I could get the Joseph Audio Perspectives while keeping the Thiels.  I like to be able to use either pair for a while.   The Thiels for me are a sort of touchstone of confidence.  Keeping them means I can experiment with owning other speakers that may be more exciting in one way or another, but I always have a safety-net speakers were everything just sounds effortless and balanced.

@samzx12
I got them from Brent Jesse Audio Tubes They are the ones listed on his site for $115 Mullard 12AU7 long plate with Halo getter. They are warm, rich, and detailed. The stock PL tubes sound glassy for a lack of a better term.

@Prof....I doubt I will be able to keep the 2.7. The store I auditioned at gave me a very good trade in price if I choose to buy the Nova's from them. 

@rushfan...Looks like they are out of stock but have rebranded Mullards for $140  pair.  Do the front 2 tubes make the most difference?