The M33 is no slouch so from that perspective it’s not too surprising you’re pretty happy overall with what you’re hearing. But there’s a big difference between liking the sound being truly moved and captivated by it, and IME that’s the next level and what can be achieved with higher-end components. It can be easy to be lulled into liking what you hear until you hear what’s possible with something much better, and then you’re not so happy anymore. Just purely as an example, inserting something like this Gryphon Diablo integrated into your system would very likely be transformative on every level.
https://www.audiogon.com/listings/lisbef10-gryphon-diablo-300-solid-state
But at this level it becomes highly personal and dependent on individual tastes/system synergy and only you can determine which components deliver the sound improvements you’re looking for. I’m just stating the obvious that there is a much higher level out there and you should do some more research as to which components likely deliver the specific sound characteristics/improvements you’re looking for. I’d also emphasize that everything matters a lot so plan on a better streamer, DAC, preamp/amp, and probably even cables. What’s your budget, and are you looking for new or used? Knowing that and having an idea of what you’re looking for you’ll at least get some good thoughts/ideas here to look into. All that said, I don’t think throwing $$$ at the T+A amp is a good idea at this point as it’d be a crapshoot until you do more research as to what else is out there. I would highly recommend traveling to some dealers/shows if at all possible to go hear for yourself and ideally demo components in your system. Anyway, just my $0.02 FWIW.