It appears the StringPort is having problems due to the 10.6.8 updates prior to Lion upgrade.
I am experiencing distorted audio output from the SP is several apps. I/O settings do not solve issue.
There are other reports around the net of similar problems with other devices.
I will set up a separate boot of Lion and see if it is still a problem there.
KMI StringPort_1650, SoftStep_VK2 v1.2 & MIDI Expander; Mac_Moore Guitar,
Roland VG 8, 88 & 99, YamahaVL 70m; OSX 10.6.8, iMac i7 2.8G QC; MaxMSP 5.1.8, Ableton Live 8.2.2, M4L, SC3, QC, cSound, etc, etc,