Characteristics
===============
 - Low impendance is better for battery powered devices as require less
 voltage. Higher sensivity means the higher volume.
 - There is open and close earphones. The sound from closed earphones 
 does not escape outside and had some reduction of ambient noise.

Requirements
============
 - Мягкие наушники
 - Fold for storage
 - Detachable cable
 - Closed cans earphones, 
 - Opion to attache usb mp3 directly


Earphones
=========
 1. Sennheiser HD380 (100 EUR, the current ones)
 2. Audio-Technica ATH-M50S (144 EUR)
 3. HD598, HD449, HD429S



Wireless
========
 - Plantronics BackBeatPro looks interesting. 
    Bluetooth (i.e. works with phone) or wired-modes. Noise cancelation. Disadvantages is price of 200 EUR 
    and only ~24h on embedded batteries.
 - Bluetooth 4.0 A2DP seems good quality, but degrades on the move. Still fine if it is above the belt.
 - Transmitting to multiple bluetooth earphones is possible with "Multi-stream transmitters". Though, expensive.
    - H-366T Mehrpunkt Bluetooth 4.0 Audio Transmitter (~ 16 EUR)
    * alternative is configuring multidevice output with paprefs 
    * buying audio Y-splitter and using simple bluetooth transmiters.