Hello there, have gained me the Behringer HA400 together with a Sennheiser HD555. I see mainly on PC films and love and especially hear loud music. Have the PC signal has always reinforced with a stereo system. This is now obsolete: HA400: Small but powerful! He is super processed completely from Metall.Netzteil is. He amplifies the Siganl very well without any noise (no noise or crackle when making loud) to be observed as is all headphone and the input terminal are for 6.3mm jack. and no cable / adapter supplied. Have him tested also times with a total of three Senn hoarse. 2xHD555 1xHD570 All three super rich sound and turn up the volume was not even necessary. Can only recommend the device!