Pretty much anything that is ok quality and set up well will impress people. I have a cheap system in my office that has led to people at work buying systems for themselves. But blow them away?
I can do two things that shock people. First, I can tow ONE of my AV speakers out about 10 degrees (at 12 feet from the listening position). That returns the center to center, and at the cost of a bit of smearing, makes the sound stage HUGE. Beyond the side walls, and floor to ceiling. (odd room, btw).
But what really does it is if I set up some stand mounts (my surround speakers) about 10 feet into the room, then tell them to "Walk between the little speakers and tell me how much of the sound is coming out of the big speakers." They walk and STOP when the pass the stand mounts, because they literally are standing in the sound stage. It is that shocking to them. Then they will go up to the AV speakers and put their ear to them.
They are, of course, not playing at all. Then I tell them the amp/dac/speakers were less than $400. And they think it sounds very, very real.
The interactivity of the exercise is what really puts it over the top, in terms of effect. That, plus the AV speakers are big, the stand mounts are small. They expect big sound out of big speakers, but not small ones. So I set them up with the big ones, and then shock them with the small ones.
