Once the system is calibrated it should stay that way unless :

- you move the speakers around
- your receiver "crashes" and loses the settings
- someone messes with the settings when you are not there
- you have free time one weekend and think you could do better this time

M60ti, VP180, QS8, M2ti, EP500, PC-Plus 20-39
M5HP, M40ti, Sierra-1
LFR1100 active, ADA1500-4 and -8