Synapse Audio Obsession is a highly regarded virtual analog synthesizer plugin that meticulously emulates the sound and characteristics of classic polyphonic vintage synthesizers, particularly the Oberheim OB-Xa. It is known for its warm, organic sound and detailed per-voice control, which gives it a "hardware" feel. 

Key Features

• Authentic Emulation: The plugin features astute modeling of Voltage Controlled Oscillators (VCOs), Voltage Controlled Filters (VCF), and Voltage Controlled Amplifiers (VCA).
• Individual Voice Control: A standout feature is the ability to adjust parameters (like cutoff frequency or release time) independently for each of the 8 or 16 virtual voice boards, creating the subtle imperfections and "organic" feel of a real vintage analog synth.
• Dual and Split Modes: It offers flexible performance modes, allowing users to layer two different patches simultaneously (Dual mode) or assign different sounds to separate keyboard regions (Split mode).
• Integrated Effects: The back panel includes a high-quality effects section featuring a studio-grade reverb (with a "Shimmer" effect), stereo delay, and chorus/ensemble effects.
• Advanced Modulation: It includes a comprehensive six-slot modulation matrix and two LFOs with "Stepped LFO" modes that allow for freehand drawing of custom rhythmic sequences.
• Modern Amenities: It supports modern features such as a scalable, Retina-ready interface, MPE (Multidimensional Polyphonic Expression), and NKS (Native Kontrol Standard).
• Extensive Preset Library: The synth comes loaded with over 500 professional-grade patches designed by industry experts. 

Sound and Usage
Obsession is highly praised for its rich, fat basses, lush pads, and airy leads. It is considered to be one of the top software emulations of an Oberheim-style synth, competing with other high-end virtual instruments like the u-he Repro. Its ability to simulate temperature-dependent fluctuations via the "Organic" knob further enhances its realistic analog character.