Why do you need so much power?

The same reason people drive 250+ horsepower cars - effortless performance. The Emotiva has WAY more power than you will need, so it will never strain. Another BIG factor is that Emotiva's are reasonably priced. I have an 8 wpc amp that costs more than the Emotiva! Your friend wanted you to get a bargain! It will certainly cost less than anything from PASS labs (I have two pass amps, not complaining). By the way 80 watts sounds only about 3X louder than 8 watts. To sound three-ish times louder than 80 watts, you'd need 800! Keep Smiling!

@boomerbillone

The same reason people drive 250+ horsepower cars - effortless performance. The Emotiva has WAY more power than you will need, so it will never strain. Another BIG factor is that Emotiva’s are reasonably priced.

while there is some truth to what you say, i would only add that there is a very important dimension of quality that matters, not just quantity of watts... if the objective is indeed to achieve great sound

Another point - you might look for actual measurements of your Tannoys if you can find them.  Many/most speakers are not nearly as efficient as the manufacturer's specs indicate.  Sometimes, the difference can be as much as 6db.

By the way 80 watts sounds only about 3X louder than 8 watts.

Should be only 2x louder. Perceived loudness is equal to
k^(1/3.5), where k is ratio of power. For 10x power it is equal to 1.93
10x power is equivalent to 10dB sound level increase equal to 2x loudness increase (3x will be sound pressure change).

@ssmaudio,  the Pass J2 is a great amp, do yourself a favor and pair it with your speakers.   I have never heard or owned an Emotiva amp.

Respectfully, 
Jose