Hi, How do you see Could I substitute the OPA604/TL071 output buffer/summer OpAmp with NE5534 or the R16-20 / R21 (22k -s ) too much for this opamp (and (of course??) external compensation needed for NE5534) Or could I decrease R16-20 and R21 to 10k or below for better NE5534 performance ? Thanx in advance Br, Pala