I wouldn't bother with OTAs. Use linearized 2164s. They're awesome. > The LM13700 varys a lot. I checked 5 pieces and they varied > between 0.1%THD to 0.4%THD in the same seting. So some > selection is needed to obtain best results. > > Later i will check 3080 and 3280 for comparison . > > I'll keep you posted.