How to steam music FROM mac/pc TO iPhone?

In my case, at home I have HiFi system and if I want to listen some music I connect my mac to my amplifier and that's it, but if I want to work, I'm sitting in like 5 meters from HiFi and I don't want to have this long wire to connect. So I started to search, my idea was to find an application for iPhone, connect amplifier to iPhone and somehow push (steam) music/sound to it via WiFi or something like that, after long searching and researching, I finally found perfect solution for this, it's application called: WiFi2HiFi

It's really good, the quality is great, the latency is good as well. 

I really recommend it :) enjoy.