A quality set of headphones will not provide tones that the speaker doesn't also provide. But, you can interpret those tones much better without having to listen to a variety of external noises. For that reason, I do believe you will be better able to hear the sounds produced by your detector than if you weren't using headphones. Frankly, I can't imagine hunting without a good set of headphones.
I like my Gray Ghost Originals. Although there are several good makes and models available, I prefer the Gray Ghosts for several reasons. First and foremost, they fit my huge melon! (hat size 7 3/4). They fit well and the padded ear cup pads (which are replaceable) make them comfortable enough for those "all day" hunts. They block out nearly all of the outside noise. (traffic, wind, curious onlookers, etc). and allow me to concentrate on only what the detector is reporting. They reproduce all of the audible sounds of my detectors very well. They will work with either mono or stereo detectors by simply flipping the toggle switch. They have adjustable volume controls. (But I always run mine wide open. ) They have a sound limiter circuit so you don't get your ears "knocked off" by that shallow aluminum can! They have a 90-degree plug and the coil cord is very rigid. All of DetectorPro headphones are quality products!
As I said, others make good headphones too. I just happen to like my Gray Ghosts the best. JMHO HH Randy