An issue with Fluance Ai41 powered speakers and external preamp

I just purchased a set of Fluance Ai41 powered bookshelf speakers and when I ran my Rolls Bellari PA550 headphone / preamp from my turntable to the speakers 90w class D amplifier and played a record it began to clip horribly. After reducing the preamp volume, I soon found that I have an issue with the volume of the Fluance suddenly dropping down during parts of certain songs with more abundant bass and high frequencies. This problem persisted after further lowering the volume of the external preamp. Eventually I disconnected the Rolls and switched to the turntable's internal preamp and this eliminated both problems. But now, although I am pleased with the sound of the Fluance speakers, I would still prefer to have a preamp attached to the system that will not impact the speakers in this manner. What is concerning to me is that at least two of the reviews on the Fluance site mentioned this very same issue with their very own PA110 preamp running into both the Ai41's and the Ai61's. If this issue exists with their own preamp, is there really ANY preamp that will not activate what is obviously a feature meant to protect these speakers?