XXHighEnd

The priorities were ever back created to

1. give the Audio Engine priority over everything else, so glitchless playback would be enbaled;
2. imply a better SQ from that.

It is fair to say that almost everybody uses the Real Time priority for the Audio Engine (referred to as "Thread Priority" in XXHighEnd's settings) while the remainder of the OS is dedicated "Idle" ("Player Priority" in XXHighEnd).

Because of this, there is no real data available about the influence at SQ and so it remains theory that having the priorities set like this contribute to good sound. It is to be noted though that setting the priorities otherwise, at least theoretically will not produce the best sound possible.

In rare occasions the priorities can help with glitchless playback. From the reporting known, only setting "Nothing" to either setting helped in those rare occasions, that bringing the idea that for such a "critical" PC each messing around with what was determined for the general OS best working, disturbs the OS heavily.

For technical reasons the "Nothing" setting does not exist anymore beyond 0.9z-6-1c, and Normal should be chosen now. This is not 100% the same as "Nothing" which just didn't change nothing, but it must be assumed that no processes exist in the OS which don't have "Normal" assigned to begin with, and if they have not, it can not be changed. So the result should be the same (or will not be crucial otherwise).