Emphasis on stereo but need a complete solution.

If the “Audio Out” on the back of the Yammy is just a front L/R line out you will only need a stereo preamp to do what you’re looking for.  IF that audio out is what I described you just hook that from the AVR into into the HT bypass (or other unused input) on the stereo preamp and also hook your streaming source into the stereo pre and you’re pretty much done.  Your 2-channel will be completely separate from the HT signal path, and all you need to do to switch between stereo and HT is switch to the appropriate input on the stereo pre and that’s it — it’s a beautiful thing.  A preamp with an HT bypass input makes this easier and more seamless to do as no volume matching is required between the AVR and stereo pre.  Alternatively you could retire the NAD and get a good integrated amp — again preferably with an HT bypass input — and that’d work too.  Hope this helps, and best of luck.

The RXV375 is useless in terms of what you’re trying to accomplish so I’d just cut bait and sell it to partially offset the cost of getting something that’ll actually work for you.  If I’m you I’d take a good look at this highly regarded Hegel H190 integrated and Yammy Aventage AVR that fall within your budget, will do what you’re looking for and will likely sound excellent in your system.  Just one idea FWIW.

https://www.audiogon.com/listings/lisb956b-hegel-h190-integrated-amp-with-dac-and-streamer-solid-state

https://www.accessories4less.com/make-a-store/item/yamrxa2a-rb/yamaha-rx-a2a-7.2-ch-x-100-watts-a/v-receiver/1.html

I was kind of hoping to keep the amp portion of stereo separate from the streaming/dac/preamp.  Just because the digital stuff goes obsolete faster than amps.

So then just get an integrated amp with no DAC/streaming capabilities and a separate DAC and streamer to plug into it — this setup still works great.  I still wouldn’t overlook the H190 though as it’s a great integrated amp and has the juice to drive your Totems.

Wow. Great find and congrats! Definitely consider the link I included above for the Yammy. Many people here have bought from them and they get high marks — great prices for basically new gear with full warranty is hard to beat, and you avoid the potential risks of buying used. BTW I’m a big fan of Yamaha AVRs for both their sound quality and, very importantly, their reliability. Happy hunting!

Incidentally, the streamer/DAC in the H190 are decent and certainly very capable of getting you going, but there’s definitely more to be had with a better separate streamer and DAC down the road if you so desire, and the H190 is a good enough integrated to that it’ll scale up and grow with it if/when you decide to up your streaming game. Looking forward to hearing what you think once it’s up and running and after it has at least 100 hours of break in on it. 🤞🤞🤞.  Oh, forgot to mention I’m also a big fan of Totem speakers — one of my faves.

Nicely done!  I should have you audio shop for me.  A wise man once said “yeah the waiting is the hardest part.”  Do you have an additional interconnect to run from the Yammy’s preout to the Hegel’s HT bypass?

Honestly, for this application I’d use anything you already have on hand unless you just feel like spending more $.

I suggested the H190, not the H120 cause ur gonna need the power.  Which one did you get?

Whew!  Yeah there’s quite a difference between the 120 and 190 both on the amp and digital side so very glad you could switch, and yes that's still a very good price for an open-box 190.  Looking forward to your thoughts. 

I'm surprised the Hegel doesn't have a sub low level output.  Not sure I need it with the Totems but seems odd.

A LFE or sub output is a feature you’d find more on a home theater oriented product.  You should be able to use the Hegel’s variable line level output with your sub if desired.