The Adcom / Benchmark comparison was a response to trickeydude’s call for a good, inexpensive amp for Thiels. Plus, I have a personal interest in the journey of that GFA555 moniker from a Nelson Pass, simple, low parts count design to a different designer's complex, high parts count design. There’s a lot to learn there including the nature of the ’improvements’, what may have been sacrificed, and different solutions applied to that original amp.
At Jim Williams’ suggestion, I am exploring his solution of upgrading Nelson’s original design and comparing and contrasting outcomes between the three iterations, plus the AHB2 as reference. I'll keep you posted.