Thank you for the lightning fast response! 

Regarding Amazon Linux, it's evolved from Red Hat Enterprise Linux (RHEL) and CentOS. While not my personal preference yet, it's required for my AWS Lambda project. Using yum, The following packages were not found:

yum install ladspa ladspa-devel 

Thank you for the clarification on LADSPA Path. I'll be sure to set that when running, not worrying about it when building at this stage.

You mentioned a need to install ltdl. I was able to install the following, also installing the libtool-ltdl dependency:

sudo yum install libtool-ltdl-devel 

While unable to enable LADSPA yet when building SOX, I was able to locate config.log, posting the full log contents here for further troubleshooting:

Thanks again for the excellent support while troubleshooting this. :)

Kind regards,

Chris