I stopped doing mods to my components and began building my own. I was kind of taken back years ago by all the people modifying CDPs preamp and amps, etc. and the prices that they were charging. I also was disappointed by seeing very little high end parts in many high priced components I repaired. Things like cheap volume controls, cheap caps and basic resistors. I first built a preamp because that is where I thought I could improve my system. I actually installed a switch that I could switch between resistors to hear how each one changed the sound by a simply a turn of a switch. People came over and told me that there is no way they would hear a difference but as I turned the dial they asked, what did you just do and then told me the differences they heard. I learned so much from swapping out different parts and how they changed the sound, improving voltage regulation, rectification, current limiters, volume controls, etc. Heck even the chassis has an impact on the sound. It was an eye opening experience and I am still learning more each day.
Happy Listening.