Would you choose 1 ou 2 subwoofers for a stereo set?

Agree with @jasonbourne71 and @mijostyn - two bigger subs. Going from one to two subs made a significant difference in both the sound of my system and my level of enjoyment from what I hear. You need big and fast subs that goes low, to augment the bass frequencies provided by your main speakers. Maybe poke around and find out what other 802 owners are using successfully.

Another benefit to using subs is the ability to high pass your main speakers, and possibly even mains that go as low as the 802s, thereby relieving the amplifier and the low frequency drivers in your main speakers from trying to push low bass frequencies.

In my case, I was able to switch out larger, full-range bass reflex (i.e., ported) main speakers for better sounding, acoustic suspension (i.e., sealed) speakers that offer much better sounding bass down to about 40Hz, and then roll in the subs from there.

You will only be able to determine whether using a high pass filter sounds better with your 802s by trying it. The result will depend on the HP filter you use, your subs, the ability of your 802s to handle low bass, the type of music you listen to, and the volume you typically listen at.