Have AKG K550's plugged into my BM as I type.....haven't got any other headphones to compare it to, I'm a fan of my friends K701's but wanted closed back myself, thought I'd give them a go. lovely lovely, so much depth and fantastic separation, but the volume control isn't half sensitive! These headphones don't take much driving it seems and I can only just turn it above its bottom spot......have emailed Stan so will see if there's anything to be done!