What’s the must-have gold standard of IEMs? What’s a good model of IEMs with a sound profile similar to the revered Sennheiser HD650s? I love that “dark”, relaxed sound. I’m looking for something that’s not too bright - I don’t need any boosts to the sibilance in my 70s rock’n’roll...

Currently been owning the HD598s for a year - love them. I've always been looking for the perfect set of headphones for me and now it seems I can afford them. I've read up on the HD 600s, 650s, 700s, and 800s. The HD 600s and 650s look nice but I'm sure that there are better for my price range...