A side-note:
@V_ad_im said:
[...] Konzerthaus Organ[...]
It might be the most meaningful thing not to use MIRx for Vienna Konzerthaus Organ at all, especially when you want to hear it in Vienna Konzerthaus - Grosser Saal. After all, that's the hall where this instrument was recorded anyway! π Just make sure to use the Release-samples provided by Konzerthaus Organ's presets by default, and you will hear the original reverb tails.
OTOH, make sure to switch off VI Pro's Release samples when you plan to use it in any other MIR Venue - otherwise you will send the recored natural reverb tails into yet another reverb.
HTH,
/Dietz - Vienna Symphonic Library