Hey
Dt150 is famous for vocals. Many musicians use dt150 for voice recording in studios..
It's mainly used by jazz singers and acoustic recordings .
Dt150 have glorious midrange( where the music heart lays)
Sound is smooth and natural, Dt150 got a big and effortless sound,It's like driving American muscle car
It's detailed hp without sounding bright, I would say it's sound on the dark side but remains neutral!
It does need amp! Without amp it will sound weak and thin...
Yamaha mt220 is ok without amp but won't sound to it's full potential without good amp/dac!
Yamaha mt220 has great isolation and could be used outside, it plays loud enough from phone/tablet/laptop but won't shine without proper source and amp.
I would get Yamaha mt220 and not dt150 if you not planing to get amp !
Yamaha has very dynamic sound with strong low end and studio like neutrality. It's a smooth sounding hp! Sound picture is smaller on mt220 than on dt150, soundstage is also smaller , dt150 is more refined more elegant, Yamaha is more agile, more in your face type of sound presentation , with hard punch and thick liquid midrange, strong low end and smooth highs.
Both dt150 and mt220 are awesome, I couldn't choose one over another so I got bought !
Hope it helpes.