You really need to experiment extensively to determine the optimum for your rig, meaning different types of filters work better on different components, as was stated above. Example: the Chang series of conditioners offers various levels of analog & digital filtering, sometimes even combined into one model with multiple plugs. Yes sometimes even straight into the line is the best way to go.
What has not yet been mentioned above, & to further complicate this issue, is that various combinations of upgrade AC cords (different makes/models) work in tandem with the filtering to produce still more variable results. It can sometimes (but not always) take you a very long time to determine which combination you most prefer.
What has not yet been mentioned above, & to further complicate this issue, is that various combinations of upgrade AC cords (different makes/models) work in tandem with the filtering to produce still more variable results. It can sometimes (but not always) take you a very long time to determine which combination you most prefer.