IMHO, it would be a sideways move. You could probably roll your preamp tubes and get a bit more warmth. The Thiels and ss AR amp both are probably a bit on the cool side so what you describe isn't a shock.
Tower speakers don't mean they're for home theater. It means they will have larger or more low frequency drivers and be able to provide lower bass and sometimes deeper and/or better defined bass.
While Sonus Faber might provide the most beautiful cabinetry and designs, I've seen, each time I tried to convince myself to buy them, alternatives provided me more of the sonics I was seeking at the same or lower pricing. All that Italian woodworking craftsmanship doesn't come cheap.
You might want to check out GR Research's youtube video where they modify Sonus Veneres. It was pretty interesting and IMHO candid in its commentary. Cheers,
Spencer