I will be using my newly built Quickie and a yet to be built Quicksand for both headphone use and maybe for speakers. What are the best headphones to pair with the Quicksand? I have Senn HD600s, Senn 598s and UE IEMs I can buy a dedicated headphone for this system and would appreciate knowing what cans you are using and others you might recommend. I know that 'phones are an individual taste, just wondering which ones you like. Thanks