boiseengineer said:
This question seems easy but has deep implications. All broadcast audio processors introduce some amount of nonlinear distortion to achieve loudness and coverage --- generating nonlinear distortion is fundamental to the operation of these devices. Manufacturers use various techniques to try to ensure that this distortion is either undetectable to the ear, or if it is detectable, that it sounds euphonic.
For a given amount of loudness and brightness, the 8600 will produce lower perceived distortion than the 8500 on almost all program material (I can't say "all" because there is no way for me to listen to "all program material" in my lifetime
Whether "lower" is "low enough" is a matter of preference. Like other processors, the 8600 provides controls to trade off loudness and distortion, so I am sure that there is some setting of the unit that sounds "undistorted" to you on steel guitars.Bob Orban