Compressed audio and uncompressed audio. Any obvious differences?

[Euphoria14]

I will be the first to admit I am no hardcore audiophile, but I was having a discussion today with a co-worker about compressed audio and uncompressed audio.

He claims there is no noticable difference between the two when played on 5.1 or 7.1 surround sound home theater systems.

Is this true?

If there are obvious differences, care to elaborate?

Thanks in advance.