The original Mylar capacitors produce a thicker mid-low frequency sound compared to film capacitors. But, the sound resolution is slightly lower.On the control amp you replaced two of the green mylars, is there any particular reason that you changed those out?
I was of the understanding that the mylar caps are generally left alone. Is a film cap just a better performer than the mylars?
The thick mid-low frequency sound of the original device is due to this green mylar capacitor.
So, The commonly referred to vintage sound reflects the characteristics of this mylar capacitor.