I currently use Grado 325 and Beyerdynamic DT150. I’ve also just got a new pair of Beyerdynamic DT990 Edition 600 OHM which obviously require a bit of driving. They sound great and are very revealing. I currently use the headphone amp in my Linn Majik DSM/2. However they do require a significant bit more volume than my other phones - would it be worth investing in a separate headphone amp for driving these phones? Is a separate headphone amp of up to £300 going to cut it? Ive used Graham Slee phone amps before and wished I’d hung onto it! Any advice much appreciated.