Cambridge Audio S30s will work and they are rated to 55hz.
"I think it is a really big mistake to have front speakers that are too small. To get decent sound quality you really need front speakers that can give you stereo sound down to 50 or 60 Hz. It seems crazy to me to have 5 speakers but only have MONAURAL sound below 80 or 100 Hz."
Klipsch RF-62II, RC-500, RS-400, SVS PC12+,
Def Tech SC8000
Harman Kardon AVR 1600
PS3, Apple TV, Sharp 70" Qattron