DVD-Video allows LPCM stereo audio up to 24/192, (with limited video bit rates of course).
DVD-Audio is required for ANY flavor of 5.1 LPCM, MLP compression is required.
The line between DVD-V and DVD-A is blurred by many releases called "DVD-A" and "HDAD" which actually use DVD-V structures and 2-ch LPCM audio. Likewise there also pure DVD-A releases with 2-ch LPCM, early JVC releases in Japan are an example (these have no menus or images, just audio).
For user-created discs, anything is possible if your software will allow it, but no DVD-A or DVD-V can exceed roughly a 11Mb/sec rate.
If all that's not confusing enough, you can also put high-res 5.1 audio files on a DVD-ROM as long as your player supports it, the player just needs to spin the disc faster to obtain the required bit rate and buffering.