This may have to be a streaming review over time as I don't have all the pieces yet, but hope to within a week. The Drop iFi ZEN accepts a balanced input and also a balanced output. Unfortunately, I do not have the 4.4mm cable. I thought I had some extra plugs lying around to solder one together, but I can't seem to find them in my parts bin. This means that I cannot evaluate the full capabilities of the amp yet using a balanced DAC or driving a headphone balanced. The ZEN CAN Signature has an active EQ designed or the Drop HD6XX. There is a button which I assume should be able to active or deactivate this feature with a corresponding LED indicator. However, this does not appear to be work. The ZEN CAN seems stuck with the HD6XX EQ mode on. I am not sure if the unit is broken or if I do not know how to use it. Either way, I'm sure this will be remediated sooner or later. The ZEN CAN will accept up to three inputs, selectable with a toggle button on the front panel. A slightly larger button allows us to select among three four different gain settings (0dn, 6db, 12db, and 18db). The photos do not do the chassis and feel of the buttons justice. The feel of the chassis is solid - as if I could use it to cleave the skulls of my enemies. The buttons have a tactile feel with a ker-dink upon a press. The volume control feels almost pneumatic. This is stuff that we've grown to expect from iFi. I think the design is kind of sexy too - like something from the OG Battlestar Galactica. Here is the back of the unit. We have three inputs which are supported. Power is provided by a 5V wall wart switcher.