Using the famous (of infamous) big green button on the front, the 1050 issues no pop through my headphones (Grado SR-80) when powering on or off.
If you're talking about turning on the 1050 using the master power switch on the back, that's something I don't, nor wouldn't, do. As a general practice, you really shouldn't have your headphones plugged in when you power up any device they may be attached to. This is just asking for some kind of pop to appear. Along the same lines, you really shouldn't use the master switch every time you power on or off your 1050. That lovely green button is pretty functional for that.