I use both programs, probably over three years now although Master Lin has said to keep different energy practices seperate from SFQ.
It takes the energy cycle from doing SFQ approximately 1/2 hour to complete after finishing the exercises or meditation so it is best to wait that long before starting Holosync or any energy practice outside of SFQ. Or going the other way ie: Listen to Holosync then wait 1/2 hour before starting SFQ.
I usually do one in the morning and the other at night.
Having met Master Lin and believe that he wants everyone to get the most benefits from SFQ, it is best to practice SFQ in it's own time and don't add anything else to it.