Agreed - everything we hear is based on the speaker/source we listen to. When I was teaching, I took my kids to see the Phila orchestra every year just so they'd hear what the actual instruments sound like. If all you can reference is a sound through speakers .... even real instruments mic'd - you have never heard that instrument. This is much more paramount with digital sound generators - the movement of air is what makes the sound, and the speakers you choose will all have a color effect on it. Personally, I enjoy using onboard speakers blended with a second source to create the sum of the two. That way I hear what I need, and the audience hears what I choose to send them. Sometime's it's different.