I was going to go for the M3 Ultra with 96 GB ram, but after reading this thread I’m unsure.
my angle of view is: you want to have as much SC speed as possible.
M4 is here better than M3, obviously.
M3 ultra makes only sense vs. some very specific usecases. It´s not "just the per se better machine".
you pointed to the point yourself,...while we pointed to that earlier in the thread already:
I’ve only recently discovered that bussing tracks routes to single core, so routing multiple tracks to same bus creates load.
Which means: you want to have as much SC speed as possible. And then 2nd, as many cores as needed.
What i can add, i had/have M4mini-pro, M4mini-nonpro, M4studio max.
My M4studio max has something like 7% more SC speed than my M4mini non-pro. I would say sometimes even close to 9 or even 10%. So there is already a win vs. SC speed with the studio max.
My M4 mini pro had slightly less SC speed than my M4mini non-pro.
The studio max runs vs. my work way the coolest of the three. ( the mini pro is gonne, i gave it back the last days possible)
RAM depends on your usage. Under normal circumstances that´s not the problem vs. your problem here, would i say.
Personally am i under the opinion that the M4 runs quite a bit quicker into crackling than the M2 does, comparing the CPU load read out from my host vs. same on the other mac, same host, same scenarios, same work, same projects.
In my opinion can this be caused by single plugins. It´s usually very hard to tell.
While the ideal buffer size with M-apples vs. my work is 64-128 samples setting, uping the buffer size can help seomtimes vs. crackling vs. single plugins, => to my belive.
M4 studio max is defnitly the best M4 desktop mac for audio work.
The small M4 mini is a great machine too if the core count works for one.
M4mini-pro was totally NOT to my liking.
i personally do not work with DAWs, but realtime play hosts. Single core based.
I can´t comment vs. DAW work. Everything i do is realtime play based.
I repeat: in my opinion is the M4 definitly prone to crackling.
I repeat that too: in my opinion can this be related to just single plugins.
If possible, worth to check vs. that.