**Maybe you haven’t heard a truly good system that delivers excellent imaging and soundstage without the aid of subwoofers.
Well yes I’ve heard plenty of those systems...
Okay, you had. Then I am not concerned that you might be as ignorant as you were on the other subject like the cable impedance issue. So let me ask you if the soundstage is already ’excellent,’ why do you need an additional subwoofer to artificially expand it. What you experienced is likely the reverberation added by the subs, going beyond what the actual music content presents. Remember, my bullet #2 in the original statement already covers my requirement for soundstage. Don’t just quote the bullet #1.
My system renders a soundstage wider than my speakers, which are set 11 ft apart, and deep enough that at times I feel like I could walk into it when such music content is in the recording. The height also resembles the actual performer’s presence. What more could one reasonably want from subs?

