For the curious, I have finally put together a cable set running my Nagra PL-L off a high-end car battery, and the improvement is probably equivalent to an upgrade to a totally new preamp. This is in comparison to running it from a variety of power products such as PS-Audio, Shunyata and Burmester...
Improvements include better handling of dynamics, especially on soaring female vocals and piano. Better timing between the interplay of musicians in jazz and rock. More natural harmonics from piano and violin. More expansive soundstage and space around performers. Improvement in background silence, especially on vinyl.
If you are considering an upgrade from your existing Nagra and can put up with the careful handling of battery cables and chargers, you MUST try batteries first. The Nagra must have been designed for this since its front panel switch has a input power voltage tester.
