The winner missing middle and spatiality

Stiftung Warentest has named in the test 5/2014 (headphones 23-209) the HD229 test winner "with the best sound", the test is to demonstrate "what models for mobile applications are good". Accordingly high were my expectations, and they were disappointed. In direct comparison with an AKG K240 Monitor on "ART HeadAmp headphone amplifier" missing the centers significantly (guitar, piano), among which the spatiality suffers. Ie., With really good headphones for stationary use, I also have a Sennheiser HD 558, this mobile Sennheiser can not keep up any more in the perceived quality. The headphone cord is a bit short (1.5 m), so I've ordered an extension. Why do I keep him? I searched for bed a smaller headset that is comfortable while lying down as the two great (in-ear headphones I do not like).