I am selling this because I purchased it last month to replace equipment, but I couldn't let go of the features of the multi-function microphone preamplifier I was using. It is in beautiful condition. Operation has been confirmed. The included vacuum tube works, but I have no use for it, so I will include a new vacuum tube (I only checked its operation once). Quoted from Soundhouse: This is a microphone preamplifier that allows you to get both vacuum tube and solid-state sounds with a single unit. You can blend the sounds of both to create a unique sound image. It also has a Hi-Z input terminal, making it recommended for use as an instrument DI and preamplifier. ■ 100% tube, 100% solid-state - a microphone preamplifier & DI that allows you to freely blend tones ■ The 710 Twin-Finity is a microphone preamplifier with a fundamentally new design that combines the warmth of a classic, retro tube with the clear, fast response of solid-state. ■ Twin-Finity Tone Blending Microphone/Line Preamplifier with DI ■ Wide range of sound making is possible, from creamy to crunchy sounds ■ 2.2MΩ ultra-high Z impedance discrete JFET DI ■ Dual-path preamplifier with 310 V Class A vacuum tube + transformer impedance solid-state ■ Frequency response: 20-100kHz ■ Input terminals: XLR (line/mic), phone (Hi-Z input) ■ Output terminals: XLR ■ 48V phantom power ■ Dimensions, weight: 89H x 215W x 260Dmm, 2.4kg ■ Power supply: 100-240V