Although there are many binaural beat sessions available which sound like music, like the gushing of a mighty waterfall or the chirp of birds, which would be soothing to play through a Hi-Fi system, using your normal speakers, you will not benefit from your binaural beats sessions if you do not use headphones.
The beats which accompany the sounds in the sessions are not physically audible to the human ear, because the human ear only acknowledges sounds over 40Hz, while binaural beat sessions target frequencies between 40Hz and less than 4Hz the base tones do not have to be extremely loud to obtain the desired effect.
Another reason why you have to use headphones during your binaural beats sessions is that the sessions are specifically designed to deliver one tone at one frequency into the right ear and another tone at another frequency into the left ear; this can only be administered effectively if you wear headphones.
A good quality set of headphones will block out all external distractions, giving you the freedom to enjoy your binaural beats sessions without having interruptions. The modern ear bud style of headphone also achieves this as the sounds from the device are delivered directly to the ear drum, while over the head headphones will have a large padding that will encase the ear and block out other noise.
Using binaural beats and headphones instead of speakers will give you the most effective sessions, where you will truly be able to experience the dynamic effects of the therapy.