Re: Audio Technica entry-mid level Headphones-AD300, AD500, M20, M35 ,T200 and T500.
^ In terms of design, the AD300 are open cans whereas the T500 are closed cans . Open cans are known for a more airy and wider soundstage . The AD300 provides the same with very clear midrange and detailed treble whereas the bass is not very powerful or lacks impact you can say . The AD300 also is extremely lightweight and you can hardly feel them on your head when you use them thanks to the 3D wing style headband .Also due to the open nature the sound leaks out of the headphone and there is not very high levels of isolation. Overall its well suited for long hours of movies ,gaming and classical music . If your music demands a lot of bass ,you wouldn't want to buy an AD300 and the T500 would be more suited.
The T500 being closed are not as airy as AD300 . They have better bass extension than AD300 and a pretty good mid + treble . The have more clamping force than AD300 as a result provide more isolation as well and very less leakage of sound . Brendon is currently reviewing the T500 so you could take feedback from him as well.
Both the AD300 and T500 are not very portable as there is no folding mechanism like the ATH-M35 / M50 . You can't carry them around on day to day basis unless you have good amount of space in your backpack .