OK, spent some more time with the amps.
It suddenly occurred to me that I don't actually have any Naim left in my system - yes I only had to open my eyes, but I had the Naim kit long enough for it to have become my point of reference.
Clearly, whether things are better or not, they will be different; and different they are.
I make no apologies for liking the Naim 'sound' - it got me back into music. Yes it's a bit obvious and worse still it's a bit 'SONY Mega Base' or 'BOSE - how can so small speakers make so much sound'... But they clearly got something right.
What I noticed as I moved up the Naim range was the reliance on that mid-range lift was less prominent. The better the amps, the less 'Mega Base' was needed to fill in the holes and the underlying class of the amps was left to do their thing.
When I went from the 282 to the 252, I found the music had more detail; more space; it was more coherent. The 282 wasn't bad, but perhaps crude next to the 252: I now look back and think the 282 was a system for my early 30's and the 252 for my late 30's; the system evolving and maturing as my tastes did.
Once I swapped my front-end for the Weiss, I found a really clean source and started to enjoy the extra detail it produced. No colouring of the music, just what was recorded - but without the digital signature. I'll refrain from using the old 'analogue' reference, but it sounded very much not digital.
The TMBs seem to be doing the same sort of thing, but they are not a source component. Their skill is in delivering the music consistently over the whole frequency range; consistently well. No need to rely on an injection of steroids in the middle to make-up for the indifferent top and bottom bits.
It was clear from early listening that they were competent amps, but it wasn't until I had spent a few days listing that I really started to understand what was going on.
My first hour of sustained listening left me a bit confused. My music sounded very different. I'm not sure I recognised it as I remembered it. The sections that I subconsciously listened out for where no longer the step up in musical delight they used to be.
What I was now hearing was a parallel shift; the whole range had improved - more detail, more pace - a more accurate representation, maybe.
It actually took some sustained listening to reacquaint myself with my music: Now I was listening to the music, not snippets that happened to sound good on my system.
Naim do a very good job of drip feeding the quality to you as you climb up their upgrade ladder. I enjoyed it. But the TMBs require you to make a pretty big leap as not to suffer culture shock.
The amps offer a very mature and refined presentation, whilst having the attack and drive to keep the 20-somethings happy.
I have thrown a pretty diverse collection of tracks their way and not once have they appeared to struggle.
I guess the question for people will be: Do you want to jump some rungs of the ladder or not?