Perhaps I should have been more clear. I don't have a standard bluray player to test with, wouldn't be asking for help if I did.
Should work, you can use things like game consoles with regular monitors, long as speakers in the monitor work with HDMI. The monitor speakers may only work with the mini din connections. Otherwise you need to check if the player can route audio in a separate stream from HDMI.
I had a look on the ASUS website and the specs for the monitor say "AV Audio Input: HDMI " so I think the sound should work fine with the proposed setup. I might just get a cheap bluray player from ebay and see how it goes.