I would double check the settings in the avr make sure you have all the speakers set to small and the crossover set to 80hz for starters. This will ensure all the lower bass is going to the sub.

As has been stated by the others to compare the sound from the sub upstairs to the one downstairs is not fair as the rooms and sub position plays a huge part in how each will sound.


Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70