Anchounio,
Of course, a second sound card solve the problem. That is because a virtual one solve it too.
Let me explain the process in detail:
- Download VBCABLE_Driver_Pack43.zip and install it (VBCABLE_Setup.exe)
- Configure VBCABLE:   - Go to Windows sound properties: Start->Run: control mmsys.cpl sounds
      (also Control Panel->Sounds, or right click speaker icon...)
   - Recording TAB->Cable Output->Properties->Listen TAB:
      - Tick "Listen this device"
      - Select your Real sound card
<<<<I am sorry, I don't know how to insert a screenshot>>>
- Configure GroovyMAME:   - We need to identify the name of the virtual sound card from GroovyMame:
      - From CMD we launch "groovymame64ex.exe -sound portaudio -v"
      - We exit groovymame (usually ESC)
      - We analize the console output taking into account lines starting with "PortAudio:"
         - We will see the same devices in each API (MME, DirectSound, WASAPI, WDM-KS, etc.)
...
PortAudio: Windows WASAPI: "CABLE Input (VB-Audio Virtual Cable)"
PortAudio: Windows WASAPI: "CABLE Output (VB-Audio Virtual Cable)"
PortAudio: API Windows WDM-KS has 6 devices
PortAudio: Windows WDM-KS: "Speakers (Realtek HD Audio output)" (default)
PortAudio: Windows WDM-KS: "Línea de entrada (Realtek HD Audio Line input)"
PortAudio: Windows WDM-KS: "Micr├│fono (Realtek HD Audio Mic input)"
PortAudio: Windows WDM-KS: "Mezcla est├®reo (Realtek HD Audio Stereo input)"
PortAudio: Windows WDM-KS: "CABLE Output (VB-Audio Point)"
[b]PortAudio: Windows WDM-KS: "Speakers (VB-Audio Point)"[/b]
PortAudio: Using device "Speakers (VB-Audio Point)" on API "Windows WDM-KS"
PortAudio: Sample rate is 48000 Hz, device output latency is 10.00 ms
...      The name of the device should be "
Speakers (VB-Audio Point)".
   - We Configure MAME.INI
      - I choosed WDM-KS API so my config is:
sound                     portaudio
audio_latency          0
pa_api                   "Windows WDM-KS"
pa_device               "Speakers (VB-Audio Point)"
pa_latency              0.001
I hope I have explained it better now  
