I have the so called "easy to drive" Legacy Focus speakers because of their high 98 db efficiency. But their low impedance (subsequent 20/20s were more difficult to drive) and 4 ohm preference make them difficult to drive. Maybe it's their 3 12" woofers. Anyway, an EAR 890 amp has great difficulty in driving them, lacking in bass and dynamics and just sounding pushed. It's a Class A 70 watt design. It sounds excellent on the Legacy Signature IIIs which have 3 10" woofers and slightly easier impedance curve.
I can drive the Focus speakers with a highly modified 35 watt Dynaco 70 which has an electrolytic cap the size of the chassis underneath as opposed to the original. Lots of power stored in that cap. They're plenty the Sig. IIIs. For the Focus speakers, I use a pair of 130 watt tube monoblocks, custom made, with 2 3" X 7" storage caps, huge compared to the tiny row of caps found in the EAR 890. I bet my big amps could drive most any speaker despite the limited wattage (although tube watts are 2 to 2.5 times more than SS watts generally, not including Pass amps or other high current ones).
I can drive the Focus speakers with a highly modified 35 watt Dynaco 70 which has an electrolytic cap the size of the chassis underneath as opposed to the original. Lots of power stored in that cap. They're plenty the Sig. IIIs. For the Focus speakers, I use a pair of 130 watt tube monoblocks, custom made, with 2 3" X 7" storage caps, huge compared to the tiny row of caps found in the EAR 890. I bet my big amps could drive most any speaker despite the limited wattage (although tube watts are 2 to 2.5 times more than SS watts generally, not including Pass amps or other high current ones).