Each of the main channels is full range (3Hz on up), and if played at reference level can potentially peak at 105dB. AFAIK the LFE channel is also technically full range, though every AVR/processor measurement I've bothered to look at indicates they will filter it at 120Hz. Of course, the LFE channel is bumped up by 10dB, meaning at reference level it can peak at 115dB.
As mentioned above, if your speakers aren't up to the task of reproducing a full range signal (and the vast majority aren't), bass management is recommended.