First, I take your point on the Decware, and Steve Deckert agreed with you! That insight extended to the Luxman even at 10 watts.
Following up. I was able to audition the Luxman SQ-N150 with the Tannoy Autograph Mini's and decided not to got forward with the Luxman. In the Tannoy specs they advocate 20 watts as a minimum. Now, in most cases the Luxman worked very well. Yet, with some recordings they sounded bright. In the case of The Clash's,"Rock the Casbah," the high treble, guitar distortion at the start of the song literally makes one take pause. Another track, from Crash Test Dummies,"God shuffled his feet," also begins with a high distortion treble effect that's normally in the background, yet in this case sounded like the worst reel to real accident you could hear.
So, okay, what's causing this ? I believe the 10 watts is not sufficient to drive the 'tulip' tweeter, in many cases. This is also causing the 'brightness' in other songs. Well, the Lumyn SQ-N150 is $3,300 and the match with the Tannoy's is simply not there. Again, Holly Cole's voice sounded amazingly great, but if I went with the Luxman's the Tannoy's would have to be replaced.
Lastly, I met Steve Deckert of Decware , whom I met at Decfest; he agreed with you. He suggested the Zen TorII at 25 watts. I live nearby his shop and may see if I can get one to audition. Though I admit I really loved the design aesthetic of the Luxman.