The FiiO E7 is adorned with both a mini-USB port and a proprietary docking port, but the latter isn’t currently used for anything save plugging the E7 into FiiO's E9 desktop amplifier. Interestingly there's a single aux-in jack, but there are two 3.5mm headphone outputs. Although that's great if you want to share the device's output with a friend, a line-level output, letting you use the E7's DAC with a different amplifier might have been more useful.
There aren't many controls on the FiiO E7, but then there's no need for more than are present. The menu button is single-function, but the exit button doubles as a power control and the volume buttons also navigate through the E7's menu system. This is a pretty simple affair, but it gives access to all the options you could want to change, so that's hardly a damning criticism.
The included volume limiter is useful if you don't want to accidentally destroy your hearing ability, and the key lock also comes in handy as the screen is left permanently on without it enabled. There's also a toggle for charging over USB, which stops the battery from degrading if you're using the FiiO connected to a USB source for long periods.
The only EQ setting is labelled "bass boost" but that's not the best description of what it does. While upping the setting does indeed increase the bass presence, it's not done in a blunt manner - at least on setting "1", bass is made fuller and warmer but doesn't feel forced or over emphasised.
In fact, depending on the type of earphones you're using, leaving the EQ turned off can make them feel particularly analytical - whether that's a good thing will depend on your tastes. We found a pair of Grado GR8 headphones benefitted from having the EQ set to "1" but a pair of Etymotic hf3s sounded good without any EQ as they're supposed to sound analytic. Settings "2" and "3" didn’t work especially well with any headphones we had available to test with, as both caused a noticeable treble drop-off.