The buttons allow you to switch between speakers / headphones / two and USB / auxiliary source without interrupting playback instantly on 2 sources. The blue LEDs are a bit gaudy (especially that of the power supply that I have to hide because it was so light) and may distract for a film, for example, but it is secondary. I use the RCA auxiliary output for connecting a Bluetooth adapter, and I added to this little system AirPlay on my iPhone and my Macbook (count about twenty).
Negative point though: the headphone amplifier is very feeble. In fact the sound is much less powerful than the headphone output on the speakers, this does not really pose a problem with good headphones or whether one is single (laaargement sufficient volume but even stronger at full power).
90 In conclusion it is a very good little amp (there is less at other brands of course, but the others did not or headphone amp auxiliary output), if you have an old pair of libraries lying around there, you can make a small monitoring system. A little more power in the headphone amplifier and the addition of a remote control would make it perfect.
