Question about audio/volume settings prior to installing aftermarket radio

Hi All,

I have a 2010 Toyota Prius with a JBL sound system. I've installed an aftermarket radio that cannot fade audio (front/back) and so the manual explicitly states that I should make sure the audio is centered prior to installing the aftermarket radio. Ok, that's fine. But now after installing the radio, it feels like the lowest volume level of "1" is actually a nice listening volume, and then going up to volume level 6 or 7 (out of 50) would be uncomfortably loud for my kids for example. Having only 6-7 volume steps is certainly not a very practical range. Does this sound like I would have needed to adjust the volume on my stock radio(something relatively low) prior to installing the aftermarket one, or would that have made no difference? Sorry, if this is a stupid question.

 

I do have a module and there are settings for the gain but mostly to INCREASE it to match the previous settings. I already have it on the lowest setting unfortunately.