I replaced the .1uf stock cap with a .1uf/630 volt Theta film and foil AudioCap from Parts Express, on my 2.0 Sex amp. Wow, what a difference! More detail in the music and the highs are smoother. Amazing that $15 can make a difference. My 2.0 is from the first production run, has been demonstrated in many audio shows and meets, and has has been complemented on the great quality of sound. Since I finished my 2.1, I can upgrade the 2.0, this is one amp I will never get rid of. Next upgrade will be the C4S boards.
Cary Chin