it sets the RXTX to transmit, but no audio comes out of the sound card to the RXTX. The display shows the audio from the mic.
Howard,
If you connect a speaker instead of the Softrock TX input you hear nothing?
In my experience if HDSDR shows TX audio then it is being sent to the selected soundcard. My first thought is that something is not configured correctly. The wrong device selected, wrong settings in the Windows audio panels.
What devices are you using?
Does the Softrock actually go into TX mode when HDSDR shows TX? I have a LED showing the presence of S12v.
Other possibilities are sound drivers.
I have known partial working of a USB device cured by removal and re-insertion and reconfiguring.
73 Alan