Thanks for the answer and sorry for replying so late. Phone broke down and had to get a new one. Budget wise not the best moment to have to buy a new one.
As I understand the T778 also has a Hypex on board. And maybe your right and I do have the upgrade bug but I am also looking for a different sound than the more ‘clinical’ sound of a class D. So I’m not sure the M23 is the right way to go.
I have been looking at some Rotel, Arcam and Musical Fidelity models. Any thougts on those brands and models?
I'm in the camp that believes that most amps do not have a sound "characteristic". Manufacturers work very hard at achieving a super flat frequency response so most amps will sound the same. If they do not, something is wrong with an amp that colours the sound. What you gain with more power is dynamic headroom. That can clean things up a bit at high volumes. At moderate volume there should not be any difference. The 100F has a 90dB sensitivity, so not a particularly power hungry speaker but you can throw a lot of power at it.
You can achieve noticeably different sound by other methods. Speaker positioning and angles will have a much bigger affect than amp replacement. Maybe not what you want to hear considering the weight of the 100F.
The room has a big impact too, like carpeting vs hardwood floors, side walls that reflect or absorb sound. Those things can be experimented with at little comparative cost. I assume the NAD has a bypass for room correction? Some prefer no EQ and just use the room correction for speaker distances. If you feel something is lacking, I would start with finding some really good quality recordings as a reference and see what you can achieve. Some material simply will not sound that great due to the mix or engineering.