spend on the streamer or on the DAC ?

FYI: the Linn Akurate DS and DSM units have been around a while. But the different iterations (0,1,2,3) have seen real updates. The current Akurate 3 with Katalyst technology is excellent. They are expensive. Another option is to buy a used older model and have a Linn dealer provide the Katalyst upgrade which replaces most of the board and the rear panel. Getting the upgrade gives you a new five year warrenty as well.

FYI, the cheaper tier is the Linn Majik line and the top of the line tier is the Klimax line. There is also the more modular line called Selekt.

Linn stuff is well made with one of the lowest repair rates in the industry. It also offers excellent software and a room EQ system called Space Optimization. 

DAC

Dac (no question)

OP: From all the above posts, and is fairly well agreed on by many:
1) The Streamer is not more important than the DAC. It could be just as important in some cases but usually less important.   More often the DAC is more important so focus on that first.
2) Given that you are striving to use high end components, the 'Synergy' of the component chain, input, output connectivity and power handling will often be more important than any of the individual pieces - and if you want to get good value, then finding the right blend often requires a lot of educated guessing, and trial and error.  See if you can buy with a good test and return policy.
Best Regards

They’re both really important.  I recently upgraded from a Mac Mini to a Lumin U1 Mini and the improvement was massive in my system.

That said, I would start with the best DAC you can afford and plan to add a streamer as your next upgrade since you can stream from your MacBook.