[neptune1230]

I need some help....Here is what I have done and the results:

amp- 1200/5ch.(4x75w@4ohms,sub ch. bridged for dvc, 1x400w@2ohms)

using the calcs, I figured 17.3 for speakers and 28.3 for sub.

I used a test cd, 50hz and 500hz, I set the amp channels for those frequencies. I used the ohm meter to adjust each channel to match calcs.
Now this is what I do't understand, I set the amp using the ear method about 6 months ago when all equipment was new. When I set the amp using the amp meter the gains are less than 1/3rd the old settings. I don't listen to music loud and have never pushed the volume past 50%.
My max setting is 64, using my old settings, I was listening @ about 15,maybe 25 with the windows down.
Now, with the new settings, I have to turn the volume to 25 sitting still and upwards of 40-45 when driving. what's the big difference? The reason I am concerned is that I am about to install some CDT's and want the system correct? Any help or comments are greatly appreciated, thanks