Wondering why a PC porting of PSGroove is near impossible? This little explanation which is based from DarkAntiMatter‘s post might help you. First, you got to understand that the PC is a USB HOST device, same with the PS3 console, so by using a USB A-A Cable, you basically will connect a Host to a Host. Which is just like connecting an input to an input. Unfortunately, this wont even work. But, the only way that a USB A-A cable would be beneficial for it, is if you had a USB SLAVE device that had a USB A slot on it.
PC USB HUBs cannot be turned to USB SLAVE mode without a customized hardware, or one big load of massively low level code, at which point all USB devices would not be working and your HUB might break as a result from this (Not saying it will, but its definitely not made for slave mode). As to serial/parallel port to USB, yeah sure that would work very good, if you want to reprogram the USB protocol, which is I’m sure many people would not even try that. So trying to port into a PC is not completely out of the reality box, as the only possible and logical way to do it, is probably with a serial to USB cable, and even that is a pretty hard for any average developer.
That is why everyone is trying to port PSGroove to the PSP console, or TI-89/TI-84+, because they are already function as slave devices, so it should not be that hard. So yeah, just nothing that could lead to a problem, but I really think that a direct USB cable from the PC is really, not possible. You guys can prove me wrong though as I’d love a PC PSGroove emulator for my PS3 console!