Why do people say low power amps should be good for bookshelf speakers?


I was in a BB Magnolia recently and they had a McIntosh MHA150 integrated headphone amp that can also do 50 watts per channel to speakers. The sales rep said it "should be good for small bookshelves but its not enough power for towers". 
I've never understood this line of reasoning.  Towers are typically more sensitive than bookshelves. Is there an actual reason a small amp like this couldn't do just fine for towers that are equally or more sensitive than similar bookshelves?
roberthz

Showing 1 response by rar1

Hi Robert -

It is a combination of factors ... right?  

1) Speaker sensitivity for sure.  2) The amplifier's continuous power output per channel measured across the full frequency range (WPC, 20 - 20,000 hz).  3) The size of your listening space.  4) How loud you like to listen or better said, are allowed to listen (apartment house vs private house, family complaints).  5) Minimum vs Maximum Power.  You should have more amplifier power than you really need as you don't want to max out or floor your amp.  Need clean power.   

It is not a tower vs bookshelf thing, per se.  It's how all these factors come together.  I assume that this is for music and not home theater, as HT really eats up power.  

Sales rep did not know his stuff or is compensated to direct sales in a certain way.

Best, Rich