While there is no easy way to tell, it would be interesting to know just how much output you have at a given volume setting with particular source material. Not that the number really matters in the end, but rather does the 1070 give a particular person what they seek?
In my case, I have loudspeakers considered inefficient, middle 80’s dB for 1 watt. As such I took the leap to a 770 amplifier and have not been disappointed. My medium room can get near painfully loud without reaching the amplifier’s limits. Would I have chosen the extra expense of a 770 if my speakers averaged about 90dB for one watt? Not likely. If 5 dB is a power factor of about 3.2, then 6.5 watts average/65 watts peak into speakers with a 90dB sensitivity rating is about the same loudness as 21 watts average/210 watts peak into speakers with an 85dB sensitivity rating. Then one has to factor in whether the room is rather “live” or “dead” acoustically – “dead” meaning that air borne vibrations are quickly “killed” or damped by surfaces in the room. This can easily make a five or six decibel difference also.
Again, the numbers can tell a story, but the user has to decide suitability.