Happened to be looking thru the AD2K+ manual on the Benchmark site, and noticed an 11/04 revision to said manual that says absolute polarity was discovered to be reversed on the analog inputs? See page 18:
http://www.benchmarkmedia.com/pdf/manualpdf/AD2402-96%20AD2K_%20Manual1mb%20.pdfI guess this doesn't matter much unless you're trying to mix with another source - and even then it may or may not make a difference - but it was news to me anyways.
Steve