When you say 10s and an 8, do you mean 3 woofers at the same time?
If so you will be better off with just 2 10s and no 8 since having tens and an 8 could cause some cancellation and loss of out put. Secondly, 3 subs on 1 amp being 2 channel or 1 gives you mixed ohm loads/ irregular ohm loads...