Only had a few months, haven't had time to use much.  Deatils below. Universal Audio Apollo Twin Duo USB -
Key Features
Desktop 2x6 USB 3 audio interface with world-class 24-bit/192 kHz audio conversion
Realtime UAD Processing for tracking through vintage Compressors, EQs, Tape Machines, Mic Preamps, and Guitar Amp plug-ins with near-zero (sub-2ms) latency
USB 3.0 connection for easy connectivity on Windows-based recording systems
Unison™ technology offers stunning models of classic tube and transformer-based mic preamps
Two premium mic/line preamps; two line 3-4 outputs; front-panel Hi-Z instrument input and headphones output
Two digitally-controlled analog monitor outputs for full resolution at all listening levels
Up to eight channels of additional digital input via Optical connection
Uncompromising analog design, superior components, and premium build quality
Runs UAD Powered Plug-Ins via VST, RTAS, & AAX 64 in all major DAWs
Audio Interface
Sample rates up to 192 kHz* at 24-bit word length
Up to 10 x 6 simultaneous input/output channels
Two channels of analog-to-digital conversion via:
Two balanced mic/line inputs
One Hi-Z instrument input
Six channels of digital-to-analog conversion via:
Digitally-controlled stereo monitor outputs
Stereo headphone outputs
Line outputs 3-4
Up to eight channels of digital inputs via:
Eight channels ADAT optical with S/MUX for high sample rates, or
Two channels S/PDIF optical with sample rate conversion
64-bit device drivers
Microphone Preamplifiers
Two high-resolution, ultra-transparent, digitally-controlled analog mic preamps
Front panel and software control of all preamp parameters
Low cut filter, 48V phantom power, 20 dB pad, polarity inversion, and stereo linking
Monitoring
Digitally-controlled analog monitor outputs maintains highest fidelity
Independently-addressable stereo headphone outputs
Independently-addressable line outputs 3-4 can be used for additional cue mix
Front panel control of monitor levels and muting
UAD-2 Inside
Two (DUO) SHARC DSP processors
Realtime UAD Processing on all analog and digital inputs
Same features and functionality as other UAD-2 devices when used with DAW
Includes UAD Powered Plug-Ins “Realtime Analog Classics” bundle
Complete UAD Powered Plug-Ins library is available online
Software
Console application:
Enables tracking and/or monitoring with Realtime UAD Processing
Remote control of Apollo Twin features and functionality
Virtual I/O for routing DAW tracks through Console
Two independent stereo Auxiliary buses
Console Recall plug-in:
Saves Apollo Twin configurations inside DAW sessions for easy recall
Facilitates control of Apollo Twin USB's monitoring features from within the DAW
VST, RTAS, AAX 64, plug-in formats
UAD Meter & Control Panel application:
Configures global UAD settings and monitors system usage
Other
Attractive and durable desktop form factor
Locking power supply prevents accidental disconnection
Easily updateable firmware