I use V4 dual Op amp from time to time in my monitoring apps. Sometimes I use V5 dual in some mic preamps for sound recording purposes. For me V4 are better for analog preamps, V5 and V6 for digital sources. V4 is very clean, but maybe little edgy on digital sources outputs… Only problems, I had with Bursons is some high noisy on V4 in some eq. and with V5 dual reliability in work…(You change me couple of them…) Regards, Dragutin