Desktop speakers and Astro A50's

So I have a 32inch LG monitor that does not have internal speakers. Ive got a set of Logitech speakers and a pair of Astro A50's im trying to make it so I can have sound out of both at the same time. Any ideas on what can be done? Also I should note. The monitor has 2 usb ports, 1 display port, and one audio port. The Astros have a base that the headphones sit ontop of but the base has a USB and optical cable, but I only use the USB connection on the base. Now individually I can get them both to work by changing my speaker settings on my PC. Any tips or tricks to have both working at the same time? All ideas and feedback would be greatly appreciated!
They only way I can think of is through a 3.5mm splitter.  You would run the analog out of your soundcard to the splitter, then connect your Logitech 3.5mm cable to the splitter, and use a 3.5mm cable from the A50 base station to the splitter.  Plug the USB cable of the Astro A50 base station to the PC for power, but on your audio output, assign the analog audio out as your primary.
This will not sound as good as using the USB DAC or the optical input, but it will work.