The closest that Sony had to something like that was the PHA3, which had an output of 320mw. See here:Maybe time for Sony to do it again .. just bypassing the amp section, like almost all other brands do it these last years.
I know Sony don't have any portable pure amp (with no DAC) in their catalog ... so the chance of such feature like a real line out is very tiny.
http://www.sonypremiumhome.com/high-res-dacs/PHA-3.php
It was designed well but sounded a bit flat, and is almost certainly out of production now.
But pure portable amp, no.