Bought powerful/expensive Amp+Speakers but plan to use an old preamp , am I crazy?

Nothing wrong with the NAD, just that the rest of your system (well maybe excluding the Node 2i lol) is at so MUCH of a higher level.

Certainly it’s fine to enjoy for now, and this is CERTAINLY a reasonable upgrade path you’ve chosen - you don’t have to buy everything at an equal level all at once - but I would plan to audition some good preamps (tube and SS units) in the near future so you can tap into the fully potential of your excellent system!

Here’s an internal pic of the NAD pre from the web - looks fairly solid, discrete transistors instead of opamps or ICs. But the parts like resistors & caps are very basic. A good modern PCB or P2P and quality modern parts can be much better and more appropriate to the rest of your system.

Mac is tuned for Mac, if you listen to rock makes little  or no difference.

If jazz a bit , classical a lot .

You are not crazy.   That's a good preamp.   Of course, a side by side listen is always best.

Yes you are crazy. We are all crazy. The world is crazy. That said, do what makes you happy even if your old preamp will hold back your new rig. 

Unfortunately the preamp is really the brain of the system and impossible to dismiss. So much so that I just forked out for a PS Audio BHK preamp. Should get it mid week 🙂