The way WASAPI is handled was changed recently. In short, what you are seeing in v183 was a "bug" - the audio output was no different from v182 or v189.
Previously 24-bits output in a 32-bit container was labelled as "24-bit" output.
With the new WASAPI update, this was listed as being a "32-bit" output; because it's 24-bits of data, inside a 32-bit container.
This was updated to more accurately reflect what was happening, so you now have "24-bit (padded)" to reflect that Media Center is outputting a 24-bit signal inside a 32-bit container. (
24-bit padded with zeroes to fill a 32-bit signal - essentially the same as adding more zeros at the end of a decimal)
The DTS files decode to being 32-bit native, I believe.
So in v183 when "24-bits inside a 32-bit container" was listed as a "32-bit" output, it appears to be bit-perfect, which is why you see "direct hardware connection".
But in actuality, "24-bits inside a 32-bit container" is
not the same thing as a pure 32-bit output, so it is not a "direct hardware connection" as the decoded 32-bit signal has to be converted to 24-bits.