by Fretsource » November 19th, 2008, 6:33 am
I don't know Perischetti's book, but the 2 books are dealing with different subjects. Piston deals with traditional "Common Practice" harmony which is the harmony empoyed by Bach, Mozart, Beethoven, Tchaikovsky, etc. up until about 1900.
By the turn of the 19th/20th century, new concepts were being introduced, such as atonality, serial composition, etc. This is what is now broadly referred to as "20th century harmony".
What's important to note though is that the harmony found in most rock and pop music is almost all "tonal" and relies heavily on diatonic scales, and so has far more in common with Common Practice harmony than with 20th century harmony.
So, if you're interested in learning more about keys, cadences, I, IV, V and other tonal chord progressions, extended chords, modulations, etc I'd stick with Piston or any other book that deals with Common Practice harmony.
If you're interested in the practices of modern classical composers, then the Perischetti book will deal with that.