I just want Dorico not to play an instrument, while I am improvising on my (midi) keyboard

[Mark_Johnson]

This is the way Dorico works, with midi going through the program. See this post:

Quick way to switch to piano sound

When composing anytime I touch my MIDI keyboard I want to hear a piano sound and never the sound of the last staff I was working on. I leave standalone VST player open with a piano sound loaded, use a software MIDI router to send the MIDI signal to multiple ports simultaneously (on Windows I use Bome but there are freeware MIDI routers too), then in Dorico in Preferences/Play deselect Enable MIDI Thru. The option to select a VST for all incoming MIDI info would be a great feature so Dorico coul…

If you need step-by-step instructions, try this post.