The Dayton speakers (and the Pioneer to a lesser extent) with the T-amp will lack low-end bass compared to the Klipsch ProMedia 2.1. However, the Dayton speakers should produce great music for the money if you are willing to have the speaker not hit the low notes and not make you feel it in your chest.
The Klipsch Promedia 2.1 have strength in volume. They will gladly power a house party and have a some decent bass kick (although it isn't the deepest base that rattles your gut). The T-amp powered & sub-less solutions above just don't have this capability. While the Klipsch Promedia speakers can play music, if you listen closely to voices and natural instruments, the timbre just isn't right. I've found that my Klipsch Promedia 2.1 speakers don't give me the "musician in the room with me" feel that my main stereo system gives me, although to be fair, computer speakers at this budget rarely can achieve this.