Topic: just an advice...

Good morning to everyone!
i'm an happy fireface 800 user and i need a little advice. I would like to buy an analog summing device, so i need to expand my outputs analog channels on the ff800. I need an extra converter. I have 2 solutions, the adi 8 ds and the adi 8 qs.
I noticed there's a lot of difference(price!!!) , but i only need 8 channels, no more, so what's best for me? I work with a resolution of 24 bit 48.000hz.
Both machines uses the same converters?