It clearly isn't 'necessary' to purchase the matching Concept 20 stands - but I would highly recommend it.
The Concept 20 speaker, in common with every other stand mount design, will work best on a very good speaker stand.
The Concept 20 stand is an incredibly good speaker stand. So, not surprisingly, the Concept 20 (and just about every other similarly sized loudspeaker) will deliver its best sonic performance when positioned on this stand.
Best regards
Steve Reichert - Armour Home (Q Acoustics)