Hello,
I've got a Snow Leopard 10.6.8 guest running on a MacBook host (10.10.5). I'm using the latest version on Virtualbox (5.2.16). I use an external USB sound "card" on the host, an ASUS Sonar U7, for line audio input, although this probably isn't pertinent to the issue (see below).
I have no audio into the guest from the Line In port of the U7 sound device, the host microphone, or any other incoming audio source from the host into the Snow Leopard guest. No problem with those signals on the host, also no problem with the audio output from the guest to the host, through the U7, and out the speakers. I have no problem getting the sampled audio from the line input into my Windows XP or Linux guests, either. I have Audio Input enabled in the Settings for the guest, and am using the CoreAudio drivers and the Intel HD Audio controller. (I've tried the other available driver/controller combinations and they either kill all audio or are no better).
Anyone else run into this? Anyone know why? And, most importantly to me, any suggested solutions?
Thanks.