E07K with L7 makes it so that you can use E07K as a DAC with whatever external amp you want(most, depends on input method)
the E07K is portable amplifier for DAP's with a DAC for travel, work, or home purposes with a built in EQ.
Making it versatile
Adding the E09K which is the updated desktop amp from FiiO allows you to dock the E07K into it. This then uses the DAC of the E07K with the amp of the E09K. You can choose to keep E07K volume control and EQ active through the LO Bypass switch.
Adding the E09K just adds an external amp. The L7 with another external amp does the same thing. The combo of E07K and E09K just looks good as it docks right in and with sound signatures that work together.
You could go with another external amp or the E09K. No real difference other than looking good and a matched sound sig(which isn't even a big deal for this price range for most people).
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