TX-81Z Low outputs \ Anti-Aliasing mod?

Hi, 
 

 The outputs on my TX-81Z are pretty low in volume and require the gain to be almost at max on both of my consoles.
 

 My electronics theory isn't really all that but is there a way to change the gain of the output stage by changing a resistor?
 

 Also I'd like a little more dirt on the output so it sounds more like my DX-100, can I change the cutoff of the output anti aliasing filter?
 I think the LPF is set by the 0.001 and 0.015pf caps on the output. I tried shorting these with a screwdriver but the output just gets lower.
 

 http://glitchscience.net/glitchscience/guides/TX81Z/TX81Z_Sch.jpg http://glitchscience.net/glitchscience/guides/TX81Z/TX81Z_Sch.jpg

 

 On the Yamaha FB-01 it's output configuration is a little different but Yamaha originally fitted the wrong capacitors to the ones on the schematics relating to a muffled output;
 http://llamamusic.com/images/FB-01_Schematic_Segment.jpg http://llamamusic.com/images/FB-01_Schematic_Segment.jpg

 
 
 http://llamamusic.com/images/FB-01_Schematic_Segment.jpg 
 
 http://llamamusic.com/images/FB-01_Schematic_Segment.jpg http://llamamusic.com/images/FB-01_Schematic_Segment.jpg 
 
 
 View on llamamusic.com http://llamamusic.com/images/FB-01_Schematic_Segment.jpg 
 Preview by Yahoo 
 
 
 

 

 http://llamamusic.com/fb01/ http://llamamusic.com/fb01/