you can try to mine in solo and see your luck but it will take a very tough patience to wait for the block to be mined if ever, with the current diff trend it will also be very frustarting, there is a chance that you will never find anything
a pool is recommended unless you can produce 1 block every two weeks, this is my startegy here, so you can have the chance to hit one before the diff change at least...
Can you even still mine?
yes it's profitable, bitcoin minign is not the best mining but it's not bad now with the current bitcoin value
Thanks for your reply. So you think its wise to start with 5 s9 machines and grow from there?