Connecting 1 headphone to 2 amps - how?

[TKEblue]

Would a small mixer work?

[Cosmiceddie]

I need help. I have a Boss Katana Head and a Roland JC-40 Jazz Chorus amp. What I want to do is to switch between both amps by using an A/B box. So far so good...

In addition to this I want to use both headphone jacks together by using only one headphone. That is I don't want to switch between 2 seperate headphones which would be annoying, wouldn't it?

Can someone tell me how this works? Do I need any device in between the headphone and the 2 phone jacks?

Thank you.