In 1993 the world was introduced to a unique concept called Z-Plane Filtering from a synthesizer developed by E-MU called the Morpheus Z-Plane Synthesizer.
Z-Plane filtering enabled the user to create an entirely new class of sounds unattainable with synthesizers that operate with a 2 or 4 pole lowpass filters.
The Morpheus Z-Plane Filter Synthesizer featured 197 filter models, up to 14-pole filters and 3 control axis: X, Y, Z. This essentially gave the user independent control over 7 filters simultaneously.
The Z-Plane filter pioneered a new sound that was unique to E-MU, and the samplers such as the E-MU E6400 Ultra Sampler became a cornerstone of the musical style Drum and Bass.
With popularity of Eurorack Modular Synthesis, the co-founder of E-MU Dave Rossum created a new line of modular synthesizers called Rossum Electro-Music and has since released many modules that reflect some previous E-MU synthesizers and sequencers.
A new module recently released called the Rossum Electro-Voice Morpheus has taken the Z-Plane Filter technology to Eurorack format giving users the sonic exploration into unknown territories.
Check out this original video by E-MU describing the Morpheus and Z-Plane Filtering