Mackie 808S, Behringer Powerplay 8000 headphone amp

For small club gigs, I generally run a Mackie 808S power mixer.  I run the 
main, FOH speakers out of one amp on the 808S, and the monitors out of the

other amp.  I want to run some in-ear monitors from the Monitor Out of my 
Mackie 808S into my Behringer Powerplay 8000 headphone amp.  Otherwise,
I'll 
still control the mains with the left amp and the monitors with the right 
amp - all in mono of course.

 Does anyone have some knowledge concerning the possibility of causing any

damage to my Mackie 808S if I don't hook up any monitor speakers to it in 
the process?  I know at least in the old days you could do some damage to
an 
amp if you didn't run any speakers yet had the power turned up.