I just received a new Macbook Air at work.
I loaded Sibelius 7 with all of the updates as well
as the sounds with all of the updates.  I
loaded VDL 2.5.5 and updated the service
center, etc.  When I play back my file,
marching band and battery percussion, I
can barely hear the percussion.  I went into
the mixer and any adjustment do not seem
to help the matter.  I have attached a screen shot of
my mixer.  I know you can go into transform live
playback and increase the velocity for the battery, but
there's got to be a better fix. 

Hey Neal,

My first hunch is that maybe you aren't actually using library version 2.5.5. Depending on how you installed everything when you got your new machine, maybe it wasn't installed correctly.

Here's an article that explains how to figure out which version of the library you're using:
https://www.tapspace.com/support/faq/index.php?action=artikel&cat=4&id=127&artlang=en&highlight=version

Be sure you're using Kontakt 5 with Sibelius 7.

Worst case scenario, delete your VDL library folder, then do a new install of VDL 2.5.5 by carefully following the [url=http://youtu.be/rATGBDpUdZ8]FRESH INSTALL instructions[/url] that come with the 2.5.5 package.