My 211's boast 85 watts of a tube power, but when I tried them on a speaker that dipped down to 4 ohms in the lower mid - bass range, it resulted in an anemic balance.This could very well have been the output transformer, being 8ohm. If it had a 4ohm tap it could have been a different story, also Lampi may use no or very little negative feedback this will also have a bearing if it can drive a lower impedance as well. (having feedback lowers the output impedance)
The amp I linked to from reading on the web has user adjustable negative feedback (which lowers the output impedance) as well as 4ohm taps.
Cheers George