Colorsound Mighty Atom mini amplifier advert from July 1974:

Ever thought a tiny portable battery-powered amp could _ pack a punch to startle the toughest roadie? This latest sensation from COLORSOUND will! A mini amplifier with a powerful 5-watt kick will improve your style — more time to practice — anywhere! In the truck, dressing room, or in her apartment! - Perfect for off-stage tune-up, or just plug in a microphone and you have your own portable P.A. System Try this Mighty Atom at MACARI’s in Charing Cross Road — you'll be amazed. Available in six colours. Who else but COLORSOUND could bring you this outrageous power pack? Size only 9"x6"x4" DESIGNED AND MANUFACTURED By: Sola Sound.