I've got an Ibanez BTB510E 4-string and I recently replaced the Bartolini USA dual coil pups and NTMB preamp with Nordstrand Big Singles and an Audere Classic 4-Band. The Barts sounded good but they were hardwired in series and the top end was too muted for me. The Bartolini NTMB's treble EQ point was too high to add clarity without adding harshness and the bass EQ point was too low to add girth without adding boom. Big Singles definitely have an aggressive sounding single-coil tone. In passive they sound a lot like a 50's Precision Bass single coil - definitely thicker sounding than a Jazz Bass single coil, with less top and thicker mids. The genius EQ points on the Audere allow me to get a VERY similar tone, though, by diming the treble (1.92 KHz), fuly cutting the high mids (800 Hz), half cutting the low mids (200 Hz), and half boosting the bass (172 Hz). I A/B'd my bass against a Fender 60's RI and I got an almost identical tone out of it with the neck soloed and both pickups on. The bridge tone isn't the same, but then my bridge pup is close to 70's Fender location. The nicest thing about the Audere preamp for me is the treble EQ point. I like clarity in my tone and they chose an EQ point that gives clarity without any harshness or icepickiness.