USBMix4 – Four Channel Mixer / USB Audio Interface – ART Pro Audio
ART USB IV 4x4 USB Audio Interface | Sweetwater
Amazon.com: Tascam US-4x4HR 4 Mic 4IN/4OUT High Resolution Versatile USB Audio Interface for Recording, Streaming, Podcasting, Songwriting : Everything Else
Amazon.com: Tascam US-4x4 USB Audio/MIDI Interface with Microphone Preamps and iOS Compatibility : Musical Instruments
4 Channel Audio Interface Sound Card for Recording Professional Portable with Loopback Monitor for Audio Equipment - Walmart.com