• British High-Gain Amp emulation based on Marshall® stack
• Power Amp Drive Control
• Built In 4x12 Cabinet Emulation
• Realistic Tone Controls: Bass, Mids, Treble, and Presence
• 4X Up-Sampling Engine with 64-bit Floating-Point Internal Precision

Several products.

The Guitar Amp Sims were quite popular. It is questionable whether this software will be further developed. 

It is still available for purchase here: KVRaudio + Cherubini + Alto Music

Studio Devil Amp Modeler Pro

• 15 Preamp Models
• Authentic Tone Controls: Gain, Bass, Mids, Treble, and Presence controls
• 3 Power Amp Models with Drive Control
• Impulse Modeler / Cabinet Processor 
• 32 Studio Devil Cabinets 
• 7-Band Graphic-EQ with Master Level, 3 Modes, and Pre/Post Switch 
• Sweepable Parametric EQ
• Wah-Wah Effect
• Compressor / Sustainer
• 4 Studio Quality Modulation Effects: Chorus, Flanger, Phaser, and Tremolo
• Echo / Delay Modeler
• World-Class Reverb
• Noise Gate 
• Built-In Chromatic Tuner and Level Meters
• Import and Export Presets and Banks via XML files 

Studio Devil Virtual Guitar Amp II

• 18 Preamp Models cover every range of playing styles and modeled using Studio Devil's proprietary digital vacuum tube modeling technology
• Authentic Tone Controls: Gain, Bass, Mids, Treble, and Presence controls
• 18 Cabinets from Red Wire Impulses®
• 2 Studio Quality Modulation Effects: Tremolo and Chorus
• 2 Delay Effects: Echo Modeler and World-Class Reverb
• Noise Gate
• Built-In Chromatic Tuner

Studio Devil also offers Bass Amp Sims: Virtual Bass Amp + Virtual Bass Amp Pro.