Never tried the AQ Pegasus, however, there is a reason that the Thunderbirds are twice as much as the Pegasus.
Currently, I own the AQ Thunderbirds. They took quite a while to fully burn in, but today, I am really amazed at how well the soundstage is lit. At times when there is a solo guitar or a sax etc. it seems like it jumps out at you. Very impressive.
Check out my review.
ozzy