Most amplifiers today have a crossover built in, but the built-in crossovers are designed for convenience not sound.  An audiophile level crossover would be too big and too expensive to build into an amplifier. With a built-in crossover you are trading sound quality for convenience. The Zapco electronic crossovers are designed for people who don’t want to make that trade. Zapco crossovers are designed to provide the very best possible sound quality, and the versatility needed for the most advanced sound systems. The Zapco ASP-X4 is definitely the “Mac Daddy” of Analog Electronic Crossovers.  This unit was designed originally to compliment our new LX models of the Zapco Z-Series amplifiers. The LX are no-compromise, no holds barred, sound quality competition amplifiers and have no preamp functions other than input sensitivity. It takes a special crossover to meet the standards of an amp like the LX Series, and the ASP-X4 has just what it takes, and then some. To begin, the very same high end audio grade Elna Silmic ll capacitors and OP275 op-amps used in the LX amps are also used in the ASP-X4 (as well as in the other Zapco competition grade processors).  Another important factor in the sound quality is the quality of the control pots. They need to be clean, precise, and must not add distortion. Zapco went out the the maker of the finest pots around and had out own custom high precision pots built for our competition grade processors. Then we built in all that Zapco versatility. With a high pass, a low pass and 2 band pass filter systems you can run a 3-way system or a 4-way system. You can even have an active 3-way system and a full range rear fill. And with the dual input system you can fade between the main 3-way system and the rear fill. For that extra little touch… the X4 is designed to match the Z-series chassis. Since we assume this crossover will likely be displayed with the amps, we have illuminated the clear plastic protective cover for that extra touch in the installation. Features and Functions  Extremely versatile for 2-way, 3-way, 4-way, or 3-way plus full range to fit the most advanced sound system Two band pass outputs Dual inputs allow fading between the main 3-way system and the rear fill Clipping indicators for each output Switchable 12/24dB sub crossover Remote power supply Selectable ground reference for noise elimination 9.5 Volt RMS line driver Specifications  THD < 0.01%THD Signal to Noise Ratio > 110dB Stereo Separation 90dB Crossover Slopes 24dB Preamp Output 9.5V RMS / 14V Peak Dimensions in mm: 190(W) x 39(H) x 214(L) Overall: 190(W) x 39(H) x 245(L)