I've decided to upgrade my headphones and decided on beyerdynamics DT-990 pro (250) ohms. Thing is that I need to buy a amp/dac with it too. My primary use is gaming so I need a great amp/dac with virtual 7.1 surround mode. I've come across sennheiser GSX-1000 but they only power up to 150ohms headphones but I've heard great things about the 7.1 surround mode on that model. So can anyone suggest a good amp/dac that can power dt-990 with identical surround sound capabilities? I am really confused and already have a headache searching for it. Thanks.