Audio Advice Sought - Simultaneous Headphones and Speaker

Hi
I have recently built my first Desktop. Bit like a Meccano set (yes I am that old). My problem is that I am hearing impaired and want to use my headphones to listen to programs we watch on the TV (from where we have them stored on the computer), while my wife listens to the speakers. The dialogue is too quiet for me, and the music too loud.

We use an HDMI cable for the video from the graphics card (AMD Radeon R9 390) to the TV, but have to make alternate arrangements for audio. I have set up a bluetooth connection to a BOSE Soundlink Mini using Blue Soleil software (the bluetooth connection from the mobo - that I paid extra for over the standard Z87 - does not work). I have my headphone plugged into the front sockets on my desktop. The Z87 uses Realtek HD Audio Manager.

I can use either the headphones or the speaker, but not both. Obviously I want to use them simultaneously.

I have looked everywhere on-line and through the Windows info and I am now very confused. To a luddite like me this should be easy to do.

Can anyone offer advice please.

For analog audio, not HDMI, a simple solution is to connect a Y connector at the speaker output (green) and then connect both headphones and speakers. See picture. But connecting the HDMI cable enables HDMI audio by default. You may have to change that from Playback Devices (right-click on the volume icon).