Do you use a Subwoofer when listening to stereo?

If you are using a 2 way crossover rolling the 804s off say at 100Hz 24db/oct several things happen. You will increase the headroom of the satellite system. Essentially, it now has more power to spare.
You will drop the distortion levels of the 804's woofer. Everything else that woofer carries will be much cleaner. This all assumes at least two subwoofers adjusted correctly. Subwoofers set up incorrectly will more than likely make things worse. Unfortunately, in most systems subs are set up by trial and error. Then you have to deal with room acoustics which sub performance is very sensitive to. This is an important reason why multiple subs are required. I and others seem to have landed on 4 subwoofers as optimal. Ideally, you have digital control of crossovers, EQ and time and phase alignment. You measure the sub from several points in the room and overlay the curves. Peaks or troughs present at all locations are due to the subs performance and need to be corrected. Those that vary from one place to another are due to room modes. Correcting these is a waste of power and does not make anything sound better except at one specific point in the room. It will also add distortion due to higher loads on the driver and amplifier. If the bass does not sound good at the listening position you can start EQing the bass to neutralize some of the modes at the listening position.
Without digital bass management setting up the woofer depends on somebodies interpretation of the sound. Then, trial and error adjustments with the crossover and position of the speakers. It really is hit or miss. In many instances subwoofers should be avoided.

I run a pair of subs with nmtched amp and preamp to my main speakers.  It allows me to listen to music I would otherwise avoid, since I have no tone controls  Mainly old LP's.

I use two Velodyne DD-15's with no xover for the mains. I can turn them off with the remote if I want to but usually keep the on.

Hello emerging soul,

     I’m thinking you’re probably getting a bit overwhelmed and confused right about now, due to all the varied, pro and con advice you’ve been receiving on this thread about subs.
     It’s not unusual for some groups of audio enthusiasts to be against the use of subs. One group considers themselves ’traditionalists’ or ’purists’ that accept, without challenge and regardless of evidence to the contrary, the long standing audio hobby trope that subs shouldn’t be needed or used and just continue to parrot this outdated and misguided belief.
     Other overlapping anti-sub groups, that may or may not consider themselves audio traditionalists or purists, consists of those who have never experienced the sound quality of a good system with 1 or more subs optimally incorporated and those that have attempted to integrate 1 or more subs into their own system but perceived the results as negative for some reason. It’s important to note that individuals in this latter group could have perceived poor results from their attempted sub incorporations due to not following reliable and proven methods of incorporating 1 or more subs into a room and system.
     My main point is that it’s fairly common for individuals, even among otherwise knowledgeable and experienced Audiogon members, to be unaware of these reliable and proven methods of incorporating 1 or more subs into virtually any room and system. I believe this lack of knowledge and experience explains the opinion of some that incorporating 1 or more subs is difficult or not possible.
     My intention is to urge you not to become discouraged by the sub naysayers, they just don’t know what they don’t know. I can assure you that, if you follow my advice, you’ll be able to very successfully incorporate 1 or more subs into your room and system. Rest assured, there are very effective, and fairly simple, methods of reliably and effectively incorporating 1 or more subs into virtually any room and system, regardless of the main speakers utilized.
     I’m willing and able to guide you through the process if you’d like. The only stipulation is that 1-2 subs are required to provide good bass at a single designated listening position and a minimum of 3-4 subs are required to provide good bass performance throughout your entire room.  The reasons for this are a bit complex but I can explain them to you if you'd like.

Later,
Tim

It took me a while to realize how important subs are for stereo listening, but glad I realized it. It is not only about getting good bass, which it does (get high quality subs) but you will see how the mids become rich. More the subs, better it gets, but I settled with 2 subs. Also, I agree with getting a quality pre-amp or integrated amp. Try to experiment yourself to see if your DAC can be connected to amp directly (many DACs act as pre-amp) and see for any difference in sound quality. In my experience, the sound quality was much better when I used pre-amp portion of my integrated amp, compared to bypassing the pre-amp.