If you thought Denon's Heos wireless speakers were a little too similar in purpose to Sonos' range, you're not alone. Sonos has sued D&M Holdings (the company that owns Denon) for allegedly violating "at least" four patents. The audio gear maker accuses the Denon team of making "little to no effort" to distinguish its speakers -- while they look different and have more inputs, the core concept is supposedly the same. Sonos says it's only asking for Denon to come up with "new ideas," and won't chase after royalties if the two sides can reach an agreement. It's not clear whether or not Denon plans to fight back, but it tells VentureBeat that it takes the lawsuit "very seriously" and will have a full response soon.