Can't get my XPS 15 9510 to identify/play external speakers.

Trust me.  I'm getting to the point.  But first. A funny thing happened on the way to allowing a Dell support tech to remote access my laptop.  I couldn't install a Dell Recommended update as it kept failing at 91%.  So I contacted support and the tech remote accessed my laptop.  Long story short; He somehow deleted a user account and I lost all the history on 4 games. Dell support supervisor checked the system and, while not admitting any wrong doing on the part of the tech, decided that I was entitled to some form of relief for my 'inconvenience'.  That relief took the form of a link to the Dell accessory store and the offer to choose whatever item I liked and they would send it to me free of charge.  I did and they did.  They sent it next day air.  What I chose (there was a $60.00 limit) was a pair of Logitech Z200 speakers, since the tiny Bluetooth speaker doesn't really cut it.  However (this is the point of the post).. I can't get them to work.  They are AC powered and are plugged in.  The 3.5mm cable is plugged into the XPS 15 9510 headphone/speaker jack.  The speakers are turned on. But the system doesn't recognize them.  It doesn't even show a connection to the headphone jack.  I don't know what to call them, but I'm assuming, since they are plugged into a headphone jack, the laptop will think they are headphones, and a new headphone would show up in the Sound Settings.  All that shows up are Dell S2721HN Audio Drive and Speakers Realtek Audio. It shows Headphones Realtek Audio not plugged in, and nothing else.  Nothing I do will make these work.  Maybe Dell wasn't so magnanimous after all. Anybody have any ideas?  Thanks.