The point that others have made is the N200 is the better streamer, and yes one day your Pontus II DAC may need an upgrade. But that is the good news, not bad. The fact that the N200 will better your DAC at some point, means you can upgrade the other components and the N200 still not be outclassed.
How bad would it be to get the N150, then upgrade your DAC, and find that the recently purchased N150 is now the weakest link? IMO you should be looking at a used N200 ($4,200ish several places) or an N10 (which can be purchased new at Upscale Audio for $4,699 right now).
If I had the cash, I'd pick up the Upscale N10 right now. That model was a revelation when I borrowed one and had it in my system for about 6 weeks, and yes I also have a Pontus II DAC......which I did NOT feel was the weakest link at that time.