Aeris speakers amp

I've been lurking here for a while and have gained some appreciated valuable information. I have ordered new Aeris speakers with the Wavelet. I currently have a PrimaLuna EVO 400 preamp and amp (70wpc stereo). I tried out the amp on an old set of original Legacy Focus speakers and found it was not up to the task. I then biamped the speakers with the PL driving the upper end and it seemed to just do the job. The Aeris has larger drivers on the top end and I cannot find an impedance plot to ascertain how much below 4 ohms they go. Since the Wavelet is also a preamp, I am considering sending the PL preamp back and get another PL amp to run in mono. I like the sound of the PL with the Focus and like the triode mode for some recordings. The only other amps I have for comparison is PS Audio M700's and some old PS Audio 250 Delta's. I prefer the sound of the PL over those. My other thought was to get a set of PS Audio BHK 300's but would consider others. Any advice and/or opinions for amplification would be appreciated.