The DAK Catalog was published by DAK Industries in the 1980s to supply cheap high-volume electronics via mail order services. The DAK Catalog focused on bringing new gadgets to the market. But this the Thunderwall advertisement was really about cashing in on the boombox market of the 1980s. The Emerson CTR 965 Thunderwall really ticks all the boxes for a boombox. The Thunderwall looks great. The 4 square looking woofers really give the front a look that shouts music. The 5-band graphic equalizer is standard fare for the time. Note how the Emerson CTR 965 graphic equalizer is shown in the classic Vee shape, booming out the bass while singing those peircing highs. This advertisement misses nothing.
Searching photos (wayback) on the Internet, it appears that those beautiful square speakers are just foam covers. Photos inside the box show a quad array of 3.5" woofers and two eletrostatic tweeters. The part number for the woofers are SP-1358 rated 12Ω 4 Watts musical power. In modern day terms this is quite underpowered. However you need to remember that this is a battery powered boombox from the 80s. Loudness is a relative term.