The 1660 Supers sound great and sounds like you've already done some research, and kinda already have narrowed it down, and know what you are after. But to add another recommendation I'm thinking you could also find an EVGA 1080 pretty close in price and it might offer just a tad more bang for your buck as that's also what I'm using right now with a similar setup except I only have just one large 60inch Plasma tv screen that I'm using.
You might want to even check some 2000 series cards, especially on eBay; as long as the seller is a reputable long-time member with over a 92% positive feedback score, and the card wasn't used for mining.
And you can always use eBay to at least compare some prices and see what's out there in your price range, and sometimes you stumble upon a lucky find!
Good luck!