Pros: Jack of all trades
Cons: Master of none
I really think the E07K is a great place to start with this hobby - and maybe even carry on for a while.
The biggest plus is the amount of functionality packed into a very small package - combination amp/dac with a large number of user adjustments - eq adjustments (bass + treble), channel balance for those of us with slightly different ear sensitivity, 3 levels of gain adjustment. Supports up to 24/96 driverless via USB. Can use either as a dac/amp via USB or just a portable amp via line in. Long-lasting battery for use as a portable amp or trickle charge via USB when using as dac/amp. Comes with useful accessories (bag, USB cable, line in cable, screen protector, silicone cover, bands). Can use as just a dac with the very inexpensive L7 accessory (about $7) which provides a line out. Hold button to prevent accidental keypresses. Line out bypass control (enable/disable volume or eq adjustments when using as a standalone dac).
Not going to drive your high impedance headphones or orthos to their potential, but there is a companion higher power amp (E09K - about $110) that the E07K integrates with nicely.
If that sounds like a lot of functionality for sub $90, it is imho.
Signature is slightly warm (as compared to the E17 which I found noticeably brighter). Not the king of extended bass or detail retrieval, but very listenable.Not commenting on soundstage because my own soundstage processing is not particularly good.
Very flexible and very serviceable with an attractive price and package, Even when you move on and up, this is the kind of product you may well keep around for the utility factor.