I would say it is a good idea to check every now and then how good the amp is working. it is not difficult at all, you just need a digital multimeter.
The basics in this case would be the DC offset and the output noise of your amp.
DC offset:
-Turn on amp
-let warm up amp for 1/2 hour
-disconnect all speakers and inputs
-volume all the way down (if it is integrated amp)
- set multimeter to DC voltage (millivolt range)
-connect the terminal from meter to outputs (speakers) from amp. (make sure not to short speakers terminal)
- check one channel at a time
-a good dc offset should be on the range of 0.5millivolts or lower, The lower the better!
output noise:
-same as above, but the meter should be in the AC range!
more than 10mVac, something is way wrong with your amp.
range 2mVac to 9.9mVac, the amp is not so healthy!
range 0.3mVac to 1.9mVac amp is moderate. (-80dB to -90dB ref 20Vac).
range <0.3mVac amp is good. (better than -98dB ref 20Vac)
range <0.1mVac, amp is on the excellent side. (better than -112dB ref. 20Vac)
