After going after those two groups, I would then go for a second round. This time it could be a number of things. If your target audience turned out to be different than you thought or if you have more than one target audience than you nay want to go to places where you'd find a dense populous of those people and ask me people the same Quaid to confirm the result. The other thing you may want to consider is to come up with a different set of questions to help refine your idea. Would you like product A our B better? What features would you like to see? Would you add, change, or remove anything? Just try to get a better sense of want people need and would like to see.
Lastly, when doing this it would also be a great to start collecting emails from people interested for when you launch our if you want to get further feedback from them.
This is probably the most important stage if in any product life because it will determine if you're idea is needed or wanted, how much of a demand there is, and get your product on the right track so you're not developing features people don't want and wasting time/money. Don't be lazy with this stage. Do your due diligence.