I use Brewer's Caramel. It works similar to Sinamar, but with even less flavor impact. I did pay a bit of a premium to have it shipped from the UK, though. I don't think I'd pay that price again when I could just use Midnight Wheat instead.
That roasted bitter flavor from fine-ground, highly roasted malts is often from fine particulates that take a while to fully drop clear. Cold-conditioning usually reduces this over time.