I have two m250’s, one firmware 2.2.5a the other 4.1.08a and the former is far louder than the other, both using batteries with plenty charge, playing the same MP3 file.
I find that the 4.1.08a model isn’t loud enough at maximum volume with my MP3s. The other one, I have to turn down from maximum volume to achieve comfortable listening.
To achieve approximately the same listening volume as the 4.1.08a model at its maximum volume I have to press the decrease-volume button on the 2.2.5a model 12 times.
Why would this be? Is there any kind of remedy? Do other people with 4.1.08a models notice low listening levels? Granted I’m using phones that aren’t the most efficient (Etymotics ER4S), but having two players with widely differing volume characteristics is quite an inconvenience.