Are you sure it is 10.6?
Retail discs of:
10.6 will only boot Macs older than August 28, 2009.
10.6.3 will only boot Macs older than March 29, 2010.
System specific discs will only boot the Mac model in question that they shipped with it, and not any other age of Mac.
Macs newer than July 20, 2011 will only boot off 10.7 or later, except when their hardware didn't change until a later date. In those cases system specific discs may be available from AppleCare to boot them into 10.6.
Why are you erasing 10.9?
Why can't you possibly use 10.6 Server in this configuration to resolve your difficulties:
And if they aren't with compatibility, what makes you think running 10.6 will be better?