I have bel canto ref1000 mkii and have run them with passive (DAC3 direct as passive pre) and have used a true pre both active and passive (bel canto pre3 active and adcom gfp750 passive and active) and for me the clear winner is the adcom in active mode. Just brings these amps to life and gives body,depth, slam and excitement that you miss with a passive pre. Passive is probably more neutral and accurate but something was missing til I ran the adcom active. Your mileage may vary. Try a few out in either configuration til you find the right sound!
