I'm using Dorico 3.5 with the playback template from VSL or the Elite Strings.
I'm creating a very simple score to test it out. The first measure only has 1/8th notes and the second has only 1/4th notes but when I play it, the 1/8th notes are good but the quarter notes are so much more quieter.
It seems that he's using the short detache samples for the 1/8th notes and the long, reg vibrato with normal release and attack but somehow they sound much softer...
I'm attaching a screenshot from the Play window to show the default techniques and velocities to show that's not an issue.