Boss DD-5 high cut mod alterations

[thegnu]

First of all, I'm new here. Hey, everybody.  Pleased to meet you.

I'm a relative noob to electronics, but a fairly quick study.  I did a high cut mod on my Boss DD-5--which consists of a cap acting as a low-pass filter on the effect volume pot--and I'm not completely satisfied with it.  I'm getting a switch in the mail, so that I can turn it off and on again.  I just had the idea to put, instead of just a cap, two diodes, a cap, and maybe a resistor like the clipping stage of a tubescreamer.

Would this work without an opamp, or would it make it too quiet?  Or would it blow up my DD5?

Also, I used a tantalum cap for the mod, and I was thinking maybe a carbon disc cap would make it sound dirtier.  Is that true?