Hi @dsper,
I believe that your interest in tube amplifiers and higher efficiency speakers is a good direction to pursue. With this category of speakers it allows you to focus on the all important "quality " of the tube amp and not be overly obsessed with the wattage it provides.
larryi in my opinion offered a very good assessment of the Tekton Double Impacts that closely match my listening impressions. I heard them in a friend’s audio system driven by his Linear Tube Audio amplifier and my 300b SET mono blocks. I find them to be solidly ’Good' sounding but not ’great' sounding. Certainly competitive in their price range.
I disagree with the comments suggesting they’re outstanding and trounce the competition . I disagree with the comments that say they’re junk. Hyperbole in both cases.
My friend really enjoyed the Double Impacts for a few years. He now has Omega speakers which he prefers due to (In his opinion) better midrange and more refinement. He acknowledged the Double Impacts have deeper bass with more impact. For his taste the Omegas were better overall. So Cornwall IV, Double Impacts or possibly Omgas, all worth consideration.
Best of luck,
Charles