hardened-kernel 3.7 => 3.8 loss of nouveau hdmi audio

[Moonboots]

The problem is somewhat bizarre. I've had successfully a set-up for pulseaudio, where my audio is pumped out of my monitor by hdmi from my gts 450 graphics card.
Until i upgraded to kernel 3.8 where i noticed a new "Digital Surround 5.1 (HDMI) output" in addition to the old "Digital Stereo (HDMI) output. There is no outpoint from either of these if
i boot straight into this kernel from cold, but if i reboot from the older working 3.7.5-r1 into kernel-3.8, both audio outputs are working !
The question is what is being retained while rebooting from the kernel 3.7 vesion which permits the 3.8 to work , something connect with the nouveau drivers ?

NB The problem appears to be reproduced with ubuntu 13.04 beta1 with it's 3.8 kernel