Hi Gene,
The regular "Spirit II" has only 1 layer of high tech shielding whereas the Phono "Spirit II" has 2 layers of high tech shielding, that does not add capacitance to the cable. Adding capacitance through traditional shielding techniques usually results in a duller, less dynamic interconnect.
Both cables are pretty dead quiet, especially the Phono version. I run my Lyra Titan I (with Output voltage: 0.5mV@5cm/sec) through my 104 dB efficient horn speakers with absolutely ZERO noise & hum. It is explosively dynamic with perfectly balanced tonality.
Cheers,
Pete