Do you use a Subwoofer when listening to stereo?

Treat your room appropriately first. Many full range owners who are looking for more bass find this solves their problem so much they no longer consider a sub.

The problem is that the room has a dimension and bass waves will reinforce at certain frequencies and cancel in others. So unless your bass traps are actively able to move about the room as the bass notes change they will have little effect. DSP doesn’t work because it tries to make your amplifier put out more power at one frequency and less at another. But when you are dealing with a standing wave you might be able to kill a bit of bass bloat at one frequency but you can put as much power as you want into the bass nulls and the waveforms will still cancel. So its only slightly more effect than bass traps.


If you really want to deal with this problem, the elegant way to do it is to use a distributed bass array which can break up standing waves, resulting in evenly distributed bass throughout the room. Do do this, you take advantage of the simple fact that below about 80Hz in all but the largest rooms, the ear cannot detect where the bass is coming from so you can run the bass in mono. But it is important that the subs do not reproduce anything above 80Hz; in this way they will not attract attention to themselves. You’ll need at least four subs to do this right. They need to be asymmetrically placed in the room and therefore do not have to be aligned with your Harbeths. One sub system called the Swarm (www.audiokinesis.com) is also the most well-known sub designed for this purpose. To minimize their size they are designed go directly against the wall and take advantage of the room boundary effect, to go flat to 20Hz.


This is basic physics- in almost any room there will be standing waves. I've seen audiophiles fight them for decades- only to find out that by using a DBA that suddenly all is well. If you want an elegant and effective way to solve this issue, this is how its done. 

My Stereo listening is done by streaming thru a nucleus connected via usb to a chord Hugo tt2 and then to a marantz 5014 via coaxial, then to a McIntosh mc255 and then off to speakers referred to above

So, you’re running a $5500 DAC into a $1000 AVR??? to an $8000 amp and $10,000 speakers? Dude, preamps matter for stereo listening!!! Forget worrying about subs and start researching decent stereo preamps pronto. The Marantz is absolutely killing your 2-channel performance.

Depends somewhat on the type of music you listen to and your age. I find most of what I listen to I don't need a subwoofer but my speakers will go down to around 24hz  measured with REW 

I like functionality of avr where I can view tv screen while listening to stereo.

its very easy with the marantz avr.  I just press one key on remote to change source and that’s it ( ‘video select’ is their version of independent service).  Of course all this follows pressing play on roon.
not sure if other higher end preamps will work this well.