Ljgj,
I use the level 20 triphazers (the number indicates the size of the unit as it relates to the level of correction to be applied to the signal path in question) between the amp and speakers. The higher the number of the triphazer the more the signal is corrected/conditioned. I use a level 25 Power AC triphazer on my DAC and a level 2.0 on the output of the preamp. The idea for multiple triphazers is that you would like to correct or condition as many signal paths in your systems as possible. As such, I have conditioned the signal paths between the amp and speakers, preamp out and amp in and also the AC power being supplied to the DAC unit. (You can move the AC Power phazer around to various components, to gauge, the most bang for your buck, in your system.)
Yes, the speaker triphazers are the best place to start, given that the conditioning period is shorter of the various types of triphazers.
Ken