Checking back in. I found some of the same. The Stirlings sound MUCH improved at 150-175 hrs. They started to change for the better around 100hr. What a relief!
My Leben CS600 at 30wpc is underpowered. It's an amazing sounding piece of gear, but won't suffice. It's hard to judge with the underpowered dynamic compression and it does still fall apart with complex passages. I imagine the class A Primaluna and Pass would take care of that and, to my ear, that's the case with them driven by my friends Primaluna EVO.
The Tannoy are super engaging with whatever that indefinable draw of involvement is that I just call 'musical' for want of a different term. So, I'm thinking of (GULP) selling my Leben....
Pass seems like a good match - I'm consider the INT 60 or a First Watt J2 with a Supratek pre...if the impedances match well. I haven't finished my research there and am open to suggestions!