A result of the tree framework with the filter lender, pre-echo challenges are created even worse, given that the mixed impulse response of The 2 filter financial institutions will not, and can't, supply an optimum Alternative in time/frequency resolution. Other lossy formats exist. Among the these, State-of-the-art Audio Coding (AAC) http://www.dwmbeancounter.com/QA/index.php?qa=user&qa_1=guitarnation78