So you buy an "expensive" dedicated audio card just for DTS/DDL software encoding? Than you are probably using a crap digital speaker set without a proper receiver. outside the possibility to pair it with a decent analog speaker system or good headsets, onboard down-mix and up-mix capabilities suck, that's the main reason for me. Yes, there are tons of free and paid mixing software solutions, but outside simply graphics equations most of them suck, or add noticeable CPU overhead or additional audio latency. Best onboards audio chip-set have more or less the same analogue quality of an old midrange X-FI, good yes, but only on high-range MBs... EDIT: additional reason: most of today's motherboards, outside full-ATX high-range models, do not provide analogue multi-channel output, but only stereo.