AFTERGLOW PL9929 Afterglow Wireless Headset

Problems with external speakers and Teamspeak

I am posting this here, since PCP closed my ticket without giving a single answer.
Kinda mad, and disappointed by the assistance of a NINETY EUROS HEADPHONES PRODUCER.
Hope to find a solution here.

Thanks in anticipation people
Hello everyone.
I have a problem with my Afterglow headset.

First, My PC is connected to my Hi-Fi via a Mini Jack (3.5mm), over a single to doble multi-plug (The multi-plug is plugged into the Motherboard, and I have headset and stereo plugged into it).

It has been working fine with World of Warcraft integrated in-game chat, but when I switched to TeamSpeak I have TS audio coming out from both Headset and speakers.

I have disabled the headset from the audio options in Win8 as suggested.

Here's my PC specs, just in case they're needed:

Motherboard: AsRock Z87 Pro4 (integrated Audio Realtek HD, with front plugs in the case also)

CPU: Intel i5 4670k

VGA: Asus GeForce GTX650

RAM: Corsair DIMM 8Gb (2x 4GB) 240-pin DDR3 SDRAM 1600 mhz
What's the matter with it?

p.s: My English's kinda rusty, sorry about it