Pros: Build quality, display, two headphone connections, accessories, sound quality, power, clarity, bass boost, battery life
Cons: Distortion as a DAC with multiple audio sources, has to be rebooted. Charging while used causes slight whining on high effinency 'phones
I'll be comparing it with the intergrated chipset in my laptop (Realtek AC'97) and the Nokia X6 phone with and without E7 as an amp, using AKG K 272 HD, Sony XB-500 and Sennheiser CX-300 and Audio Pro Addon One active speakers with a Tangent Evo E8 active subwoofer. Although I was skeptic whether something from DealExtreme could sound nice or not, I was quite pleasantly surprised.
E7 USB DAC vs. Realtek AC'97: Hands down, pants down, the winner is E7. No noise (don't own any really high effinency IEMs or the such but anyway), faster, more detailed lows and very clear and well extending highs in comparison. Compared to the headphone jack in my laptop there just seems to be way more separation to the instruments and music isn't some sort of a blur anymore. Then again I'm comparing it to a really low-end chipset so the difference is quite expectable
E7 as an amp for Nokia X6: overall faster, extends lower and higher, and less muddy. All in all it doesn't sound like the device is struggling to reproduce music with the E7 anymore, and the veiled muddy feeling is grealty reduced. It went three days without a charge, and that's quite good IMO. Anyway, I won't be using any power hungry cans or IEM on the go as of now, so this feature isn't too important for me. Still, it adds to the versatility and value so it's definitely a plus.
Bass Boost: I'm having difficulty deciding whether I like it or not, the sound stage seems to suffer from levels two and three, no matter am I using the speakers or headphones. It's a fun feature, but I'll have to do a lot more testing before I can say anything concrete about it.
Notes: Huge distortion and hiss under Windows 7 and Linux Mint 9/10 when running YouTube, Spotify or any flash applications. Hasa been getting quite annoying lately and I'll stop using this product because of it. Nobody else is complaining so I guess I just got a bad one, but I've lowered the SQ rating to three stars although it's really good when it does actually work.