It works nicely with ATH-M40X however it changes the sound signature just too much. Although aesthetically they are quite ugly and I wouldn?t wear them myself, they are the perfect summer shoe for children! Usually with slippers like these, I will still wear socks but I noticed that when Im wearing this, I actually prefer to wear them with no socks. LOVE these ! Soundstage is impressive for something this small and (relatively) inexpensive. I bought this for my hubby and he loves it! Not as thin as the official, but not as thick as some other competitors. 2020 9-20 UpdateOkay, so now Ive purchased 5 pairs of these. They are extremely comfortable and I can wear them all day and walk miles in them (and I have achy 57-year-old feet, legs and back). A tangled mess that looks like itll break sooner than later.