Cambridge AXA35 allows 8 ohms only — and the KEF Q150 dips to 3.7
The Q150 is 8 Ω nominal, inside the 8 Ω rating of the AXA35, but it dips to 3.7 Ω. Fine at normal volume. Go easy on long, loud bass. Published numbers only.
Everyday listening is fine. The nominal impedance of the KEF Q150 is inside what the Cambridge Audio AXA35 is built for. The dip below that rating is a caution, not a thermal overload.
At 2.5 m in a typical room, the stereo pair reaches about 99.5 dB. The second speaker and the room each contribute roughly 3 dB, which is the usual allowance for home listening. That sits 5.5 dB under a 105 dB theatrical peak, so loud film moments are where an amplifier with more voltage starts to matter.
Behind that level: the AXA35 is rated 35 W into 8 Ω, and the Q150 works out to about 86.0 dB for 1 W at 1 m from the sensitivity the maker actually published. Nominal impedance is 8 Ω.
The published minimum impedance is 3.7 Ω.
Do not declare the amplifier unsafe because of the dip, and do not ignore it during long, loud sessions: sustained bass asks for more current than the nominal rating describes. A more powerful amplifier does not erase a dip. It only helps if the current one is running out of voltage and clipping.