Ok! The coup with 320 kbps MP3 and uncompressed audio files.............................Uncompressed audio files (e.g. WAV, AIFF and FLAC) have a limitless frequency bandwidth and response.
When you compress an uncompressed audio file with a codec algorithm to 320 kbps or equivalent (MP3, M4A, AAC, etc) it cuts off the frequency bandwidth and response to around 18Khz. Any part of the waveform above this frequency (Hi Hats, White Noise, Pink Noise, etc) is deleted/filtered out of the Waveform when it is saved as the new lossy format. The lossy format at 320 kbps is around a quarter of the size of a lossless format. (this excludes FLAC though as this is half the size of WAV and AIFF)
Most sound systems (e.g. Hifis and Car Stereos) won't play back the higher end frequency spectrum very well so you won't be able to tell the difference between a lossy and a lossless audio file. When it is played back on a very expensive 'Audiophile' grade pair of headphones then you will be able to tell the difference. If a club's sound system is of good spec then you would be able to tell the difference.