Knghifi,
Upgrading to the 9.9 is like removing a bed sheet from your speakers, more clarity, wider/deeper sound stage and more palpable imaging; using Sylvania 13EM7s and Philips 5R4GYS rectifier.
Also, replacing the stock fuse with an Audio Horizon premium 1.6a fuse makes a nice improvement in sound quality but experiment with fuse direction.
Upgrading to the 9.9 is like removing a bed sheet from your speakers, more clarity, wider/deeper sound stage and more palpable imaging; using Sylvania 13EM7s and Philips 5R4GYS rectifier.
Also, replacing the stock fuse with an Audio Horizon premium 1.6a fuse makes a nice improvement in sound quality but experiment with fuse direction.