Mine was stolen last week, and I haven't been able to find the 40V version of the S4 MK3's PSU, and I really really need it for my job. It's been a while since they were in stock too, are they discontinued?
It's here and in stock:
You can find it in the catalog, under Traktor.
The page says out of stock for the US :(
Oh okay. Well, you could possibly use any PSU with that wattage and voltage (15V, 2,66A), though...
It's 15V and 40 watt, not 40V ;-)
But you don't have to get an NI PSU, you can just get any 15V, at least 2.5A, ith the same polarity and connector.
Someone in the Maschine+ forum even used a USB-C to barrel connector adapter. That way you can power it with any USB-C PD cables or even mobile power banks.