I have HIFIMAN HE500 in a really portable setup that includes Meridian Explorer as DAC/AMP and a BCL original as amp.sometimes. All these are in a drawer and i listen every night when kids are sleeping for about an hour and then i have to repack and put them in the drawer again. Meridian Explorer is good but i need something more powerfull to drive HE 500 but also portable. If it is only USB i will be happy. Is there anything like that in the market?