question about analog input

i am purchasing a 7.1 receiver, as of now i have a 5.1. if i get a audio card that has analog output, can i plug all those into my current receiver and get truehd or dtshd lossless audio? and since most cards have a digital out put, if i am watchign a dvd in my htpc and choose just standard dts, will it automaticly switch to the digital input, or is it really not needed.