Not sure about the output impedance of the Carver m4.0t.
I can't say for certain that bass levels were lower relative to other frequencies at lower volume than at higher volume for certain. It could be that the lower bass levels were just more noticeable as deficient at lower volumes. At high volumes, the rafters could be shaken by the 360 w/ch without any major tonal balance issues that I can recall. The differences in specs between Carver m4.0t and MF A3CR I recall that I could attribute this to were the power rating into 4 ohms, the damping factor, and/or the current levels available.
I can't say for certain that bass levels were lower relative to other frequencies at lower volume than at higher volume for certain. It could be that the lower bass levels were just more noticeable as deficient at lower volumes. At high volumes, the rafters could be shaken by the 360 w/ch without any major tonal balance issues that I can recall. The differences in specs between Carver m4.0t and MF A3CR I recall that I could attribute this to were the power rating into 4 ohms, the damping factor, and/or the current levels available.