Fiio 's e7 be a portable amp\/digital-analog converter -lrb- dac -rrb- . what that mean be that the e7 can be use as both as a portable headphone amplifier , and to replace you computer 's sound card when connect via the usb cable for better audio quality . the e7 offer solid construction and great value at its price point , which make it a must-buy over comparable product at this price range . the e7 come in a very compact box , when open , the box include the e7 itself -lrb- look akin to a tiny solid block -rrb- and a bunch of accessory . note that when first open , the e7 do not come charge ; it must be recharge use the provide usb cable for a couple minute . once the wait be over though , the little portable dac\/amp do wonder . use the provide usb cable with the e7 allow it to be use as a dac\/amp in lieu of you computer 's sound card . previously , I be use the stock sound card in my MacBook pro as the DAC , and the e7 completely elevate the sound quality to another level . immediately , I could hear detail across the board with my Sennheiser HD 555 . I hear entire instrument line that I have never hear before . the e7 even come with a build in headphone splitter , which be great to use to share my music with other . the construction be solid , although prone to scratch . I have drop my e7 carelessly many time , yet it remain function perfectly except that the surface be laden with many scratch . for easy to drive headphone like the Sennheiser HD 555 , the build in amplifier be plenty and will power the headphone to perfect listening level at 10\/60 . when use the e7 as a portable amp , use the provide line in-out cable in order to connect you mp3 player\/dap with the device . the sound quality leap be not as pronounced as I be just use the amp portion of the dac\/amp ; and that be probably the only criticism of the e7 for I . still though , a marginal change in audio quality can be observe with my portapro ; manifest in the form of greater warmth and slightly better bass\/highs clarity . the bass boost come in handy outside , where I be a far more casual than analytical listener . to conclude , the e7 be a great dac ; it be build with solid material and have future upgrade potential with the e9 . however , the e7 be by no means perfect . just buy the e7 to use as a amp be perhaps not a great idea , as I later find out when try to drive Sennheiser HD 600 with the e7 . still , the e7 's advantage lie with its price point and versatility , and I would definitely buy the product again give a chance . user with a great dac and\/or sound card would obviously want to reconsider though ; and those with higher end audiophile headphone -lrb- like the hd600\/dt880\/etc . -rrb- can buy the e7 if ampless but note that the e7 alone , without the e9 , can not drive those phone to they full potential .