Your single favorite component

Of all the pieces of your system you now own or have owned in the past, is there any one piece you could say is your absolute favorite piece of equipment? 

I don't know if I have an answer to my own question - I enjoy various pieces of equipment for different reasons. A turntable I've owned for 18 years, a 40 year old tuner, an amp I built myself, all in some way are pretty special to me. And so on!