I'm not sure why you would use DirectSound in preference to the modern WASAPI though.
Whatever reason you have is probably a configuration issue.
Eh, I actually am using WASAPI, more out of a "no reason not to" reason, though not in exclusive mode as I hate being unable to hear other Windows sounds. I'm sure most of you chose this media player for audio quality reasons, but myself, I chose it out of preference of having a decent interface while still being able to tinker with settings, and I loved the equalizer the moment I tried it out. However, I'm not really an "audiophile", I'm barely an enthusiast, in fact. I can't hear the difference between high-bitrate lossy like 320kbps mp3 or AAC and something lossless like flac, much less decipher whether a track has been resampled. However, I do enjoy the sound a good pair of cans or in-ears can give, recently bought my second and third mid-range earphones/headphones; a Sennheiser Momentum In-Ear and an HD 558, and just got my Fiio E07K dac/amp yesterday.
Anyways, yeah, my question was more out of curiosity, just struck me odd that a commercial media player was using DirectSound, though I understand why MC still does now that I've read other people's replies - no point in adding XAudio when it'll add so little over what's already supported.