Thomas, I'm glad to see you're still considering an Aesthetix phono stage for your system. I've not listened to the Aesthetix Rhea in my own system in direct comparison to my Aesthetix Io Signature, so I'm going to pass on trying to offer any specific thoughts regarding your first question.
As to your second, I posed this same question to Jim White, the designer of Aesthetix, when I was purchasing my Io. His reply to me as to what he heard was very direct:
The Signature provides the following benefits:
.. Greater resolution
.. More neutral presentation
.. Improved high frequency extension and detail
.. Greater top to bottom coherency
.. Better bass definition
Adding the second supply improves the sound in the following ways:
.. Added space
.. Improved macro dynamics
.. Improved micro dynamics
.. Blacker backround
.. Greater ease to the sound, less strained
Hope this helps some in your pursuit of your ultimate answer.
.
