The 1/4 inch stereo jack could be unscrewed to reveal a mini-jack that will fit portable CD players and MP-3 players. The sound quality is better than anything else Ive had as well. Its not mind blowing. The accompanying app is poorly designed, but it does enable stereo output which I think is a killer feature. I do have a wider foot, but not too wide and these definitely run narrow so if you have a wider foot, I would stay away from these. Sturdy, holds many pairs of shoes. I was a cute moment and he managed to put it together. I do recommend that if you are running AC in your house to place the bottle for a while outside to let the liquid warm up before using it in the dogs ears. I am using this to hang complete outfits for the following week -- no more zombie-like bewilderment in early mornings trying to put clothes together. We have a TINY kitchen and don’t want bottles of spices stealing cabinet space.