Improve post fader behaviour description

Co-authored-by: ronso0 <ronso0@mixxx.org>

Author: daschuer

source/chapters/preferences/sound_hardware.rst

@@ -192,10 +192,11 @@ or :ref:`setup-laptop-and-external-card`), all that needs to be configured are
 the Main and Headphones outputs.
 
 Deck and Bus outputs are intended for use with external hardware mixers.
-The are taken *post-fader*, which means they include channel volume and
-crossfader adjustments and applied effects. When mixing manually, all Mixxx
-faders needs to be at unity so that the internal mixer doesn’t affect the
-sound. When using Auto DJ the external mixer needs to kept at unity since it
+They are taken *post-fader*, which means they include channel volume and
+crossfader adjustments and applied effects. When mixing manually, all
+Mixxx-internal mixer controls (Volume fader, EQs and crossfader) need to be
+reset so that the internal mixer doesn’t affect the sound.
+When using Auto DJ, the external mixer's crossfader needs to centered since Auto DJ
 will use the internal crossfader.
 
 All outputs are usually sent to a channel pair (stereo), though they can also
@@ -209,7 +210,7 @@ Outputs
 ^^^^^^^
 
 * **Main** (Master): The mix of all audible channels, e.g. main decks, all
-  samplers, enabled microphones, and auxiliary inputs.
+  samplers, enabled microphones and auxiliary inputs.
 
 * **Headphones**: All channels for which :term:`pfl` is enabled, including
   the preview deck.
@@ -219,8 +220,8 @@ Outputs
   loopback device for video recordings etc.
 
 * **Left Bus / Center Bus / Right Bus**: All decks, samplers, and auxiliaries
-  routed to the respective side of the :term:`crossfader` picked post-fader and
-  post-effects. They can be used with an external two channel mixer.
+  routed to the respective side of the :term:`crossfader`. The busses are picked
+  post-fader and post-effects and can be used with an external two channel mixer.
 
 * **Deck 1-4**: Separate outputs for each of the main decks. They are picked
   post-fader and include effects and crossfader (for Auto DJ).