Do you use a Subwoofer when listening to stereo?

I'm an old school guy. I have a reasonably priced Paradigm 10" subwoofer parked to the left of my out-in-the-room NOLA Boxers, set up against the back wall but not too near the corner. I used my ears and a stereo test CD to match levels with the rest of my system and minimize boom. My system doesn't go all the way down to 20hz but I figure I'm able to enjoy a pretty good 30.  Bottom line (heh-heh) -- the subwoofer significantly enhances my modest system. Not only does it provide bass, it increases the size and believability of the soundstage.

i likely will get a stereo preamp and need to explore the process of switching back and forth between stereo and ht, ie. How many steps involved.

Not much to explore fortunately. If you get a preamp with a HT bypass feature you just push one button to switch between HT and stereo and that’s it, and when in stereo the Marantz is completely out of the signal path. I did this for years before I got a dedicated listening room and it works beautifully — best of both worlds really.

So, very quickly on how this works so you see how how absurdly simple this is — you just need one pair of interconnects and run them from the front L/R preamp outs from the Marantz into the HT bypass input on the stereo preamp and hook the line outs from the stereo preamp to the inputs on the Mac and you’re done. That’s it. Literally takes two minutes, and you won’t believe how much your 2-channel performance will improve — the preamp sections of most AVRs are just crap, relatively speaking.

BTW, this also works fine if the stereo pre doesn’t have a HT bypass and still involves the same hookup and pushing one button and adjusting volume on the pre to a predetermined level for watching movies/TV (can go into more detail if you might go this route) and that’s it. Start shopping for a good stereo preamp — it’ll be one of the most significant upgrades you’ll ever make. Hope this helps, and best of luck.

Yes
Yes
The only "sense" in this game is whatever sounds best.

Lotso luck finding speaker outputs on a preamp.

You push a button on the remote. I use an C2500, and a MX121, source vary from a TT, SDAC, CD, Stream, into MC275 and Class Ds, or Carys and Class Ds. Pure heaven... Easy as could be.  

Mac made a LOT of smaller monoblock... 20, 30, 40, 50, 60, 75, 100s

All were older, except the MC75, and they are still in production...

ALL of their amps are know for plenty of UMPH..

Most of music until  hip hop / rap didn't have that much sub, they were pretty much cut at 40-50 hz down, the old 78 stuff 60 hz and below.
All of my old Reel to Reel stuff is cut at 40. Big band, jazz, and country western, were all the same..

You can add BASS to the mix though...and really liven the joint up...
What most music listeners listen to is NOT sub heavy, it's bass heavy.
Subs muddy most good stereo system up because they're set WAY to high on the XO. 80 hz is the highest. Cut the bass on the mains where your subs stop.. Simple... Ya need a few though to get it Everywhere.. I don't.. Where I'm listening is just fine.
Junior (my rabbit) thanks me too. :-)

Regards

"Does excluding sub from stereo make sense?"

Only if your main speakers are full range.