Will this damage my subs or amp?

me personally i would first adjust my gain on the amp all the way down, as long as you stayed within rms ratings and you have a good match between both subs and amp you should be ok. however i have a head unit that has 3 sets of rca jacks this is allows me 2 blend the music with ease, on my sub woofer control i can adjust the frequency p and can go between +6 and -24 i keep that setting at -20, this control is a gain for the amp, (thats why i said set yours all the way down). playing with that control i blew 2 power acoustic 12s (600 rms a piece) then blew 2 kicker 12 solo baric L 5s, with just an 800 watt fockford fosgate amp. i dont know what amp, subs, or head unit you have but if you send me the model numbers i will be able to give you a better answer. i doubt that setting you descibed will blolw anything, sub or amp.