Da hat er recht.
"Mix>Return – Known as a ‘system effect’ this
uses a bus to Send a mix of the channels to the
effect, and a dedicated stereo FX Return channel
to add the ‘wet’ effect to the ‘dry’ original sound.
This is used for effects such as reverb and delay.
Choose which mix bus to use as its input. FX1 and
FX2 have dedicated FX buses. If you want to use
FX3 or FX4 as another system effect you could
patch one of the Mix1-10 buses as its input."
Ein Blick ins Block Digramm offenbart was damit gemeint ist.
Es gibt nur zwei Sendbuses. Für die beiden FX 3 u.4 muss ein Mixbus verwendet werden. Mir hatte das damals jemand aber so erklärt das die FX 3 u. 4 nur per Insert funktionieren.