Phono stage options - balanced with XLR both input and output...

atmasphere

Atma-Sphere was the first to offer a balanced phono input, back in 1989. The sales manager of ARC contacted me about how that connection was done ... and a couple of years later ARC had a balanced input. To my understanding they didn’t keep it on their preamps ...

That timeline sounds about right, @atmasphere. As I said, ARC’s balanced components date back to the mid-90s. All the Ref series preamps and phono preamps are fully balanced, differential designs.

lewm

AR is not known for balanced circuits.

You're mistaken - ARC was building balanced, differential amplifiers and preamplifiers long before the design became popular. The Reference One preamp goes back to the mid-90s, for example.