HP Pavilion dv6t 6000 Quad Edition - IDT Audio Driver Issue  

Oh! So you did a reinstall. If you can confirm that the audio is NOT disabled in the BIOS, and it worked before the reinstall, it looks like another "clean" reinstall is in store. The reinstall assumes there is no hardware problem with the audio on the motherboard, however if a proper clean install is performed and there is still no audio, it would lead one to believe there is a hardware failure on the motherboard.

Another reformat? Ohhhh boy. I wonder how many cycles a hard drive can take... :P

Since it worked before you did the reinstall and now nothing seems to get it working, another reinstall is the next step. I know its a hassle, but with so many things that can go wrong with the OS, it would be like trying to find the "needle in the haystack". Thus a clean reinstall (reformat the hard drive then install).

However, if another install does not fix the sound problem, that points to a hardware problem on the motherboard.