I have a GAS Son of Ampzilla, and I happen to have the 2-Ohm-capable Industrial Rack version.  Not that it matters, here.  But the manual says that it can output to headphones.  It does warn that the use of a resistor(s) is needed to do this.  It says each channel should be fitted with 5W 50-Ohm through 100-Ohm.

But how did people use to do this?  The amplifier only has large Binding Posts which Banana plug provisions in the center.  Do I need to make a special adapter to run my headphones off the speaker outputs?  My headphones are Sony MDR-V700's which depending on where you look, are rated at either 1W or 3W.