High frequency phase response specifications - useful or misleading?

Conventional high frequency phase response specifications of audio electronics, although easily acquired with standard available instruments, are misleading. To be meaningful, phase data must be presented as two separate values or graphs, deviation from linear phase and group delay. The first is a modified phase graph, where the frequency independent delay is subtracted out, leaving only that part of the phase transfer function which alters the shape of the audio waveform.The group delay graph shows delay vs. frequency for the spectral components of a complex waveform.