Advanced Test Jig for Series 500 Audio Modules: I sure would like to have one!

[GrievousAngel]

I have several Series 500 Extension Jig Adapters however . . . they fall short IMHO!

I several questions, besides ... What are others using & doing for Series 500 DIY testing adapters?

1. 500 extension jig design that deal with DUT balanced I/O when being measured by single-ended test devices (w/o using a calculator)?
Balanced audio signal generators are available at OK prices but Audio AC Voltmeters are typically not as cheap. Of course, if handy, DAW ADDA devices are great. BTW ... a better stand-alone ADDA module is the RME ADI-2 FS Pro. Check it out as it is a reference grade listening device as well.

2. Since most test gear share the negative (GND) terminal with its signal path system GND and maybe its chassis, w/o differential probes/modules (or even in desperation considering grabbing a gray-like VAC 2P to 3P power adapter thingy, taking proper measurements easily become a challenge. Any ideas on resolving this problem? Anyone tried that CHEAP China Differential Module for ~ $80USD? DIYer diff probe/module?

3. I know of no 500 test jig designed to easily take two simultaneous measurements 'm referring to two measurement devices on the DUT Input and/or Output.

Ideas and suggestions?

Cheers, Billy