I've tried the Creative Sound Blaster E3 several days ago. While listening to the default 256 kbps AAC, I could not find at least any sound quality downgrade compared to the lightning -> 3.5mm jack.
Unfortunately, I had no time to compare the E3 with the XB10, because the store was getting closed, however I am still going to compare these cute devices face-to-face soon.
So here are my pros and cons about each of these devices.
Creative Sound Blaster E3
+ 2 output 3.5 mm outputs, 1 3.5 mm input
+ USB DAC/amp
+ Larger battery (up to 8 hours)
+ Cheaper
- Battery is not displayed in iOS status bar (bluetooth connection icon)
- Bluetooth 2.1
- Bulkier, heavier - 44g
Astell&Kern AK XB10
+ Battery is displayed in iOS status bar in the (bluetooth connection icon)
+ Bluetooth 4.1 class 2
+ Lighter, smaller - 23g
- 1x unbalanced 3.5mm output, 1x balanced 2.5 output
- no USB DAC/amp capabilities
- smaller battery (up to 5 hours)
- pricier
The only thing that disappoints me on paper is that the E3 has Bluetooth 2.1 only, while the XB10 has the 4.1 class 2.
Probably a stupid question - is it possible to use both outputs on the AK XB10 at the same time?