Headphone Amp Sharing Connections?

[lukirocks]

Hello folks,

I bought a tascam fw1884 off ebay last week, so i went to sweetwater and bought a 4 channel samson S Phone headphone amp to use with it. My Samson amp needs a left and right output lines from the tascam, but i need the L and R outputs from the tascam to run my monitors. So...i bought a couple of hosa TRS Y cables to share the connections between my monitors and my headphone amp.

Now, just thought about this today.... Now when i need to kill my monitors to record, i'm not going to be able to use the output volume knob to kill the monitors without killing my headphone signal. Is there any other way that i can hookup the headphone amp in stereo and keep my headphone amp signal untouched. Here is the back of the tascam

http://tascam.com/Products/FW-1884/fw1884_rear.jpg

I don't have it yet, won an ebay auction last week, shipped out the 8th. There are several surround outs, could i use any of these to run my headphone amp?

Any help would be appreciated. Thanks!