*UPDATE* A buyer made me realize that the LCD display backlight was not working in the pictures. Grace did miss this in my most recent service detailed below. I have contacted them on it and they said they will repair this for an additional $150. This does not affect the performance of the m904, but I'm happy to give detailed info on this if you'd like to purchase and send to grace for repair. I also have more close-up pictures of the front panel. Just shoot me a message and I'd be happy to share those.

I just had this unit serviced directly by Grace, and it has a clean bill of health. It will ship in a brand new box from Grace. See the manufacturer's description of the unit below.

The Grace Design m904 is a high-fidelity, 2U rack-mount stereo monitor controller designed to serve as the central hub for professional project studios or mastering facilities. It provides transparent, audiophile-grade audio monitoring and comprehensive input/output switching, often used in DAW-based studios to replace the center section of a console. [1, 2, 3, 4]Key Features and Capabilities:

• Audio Quality: The m904 features premium 24-bit/192kHz DAC technology with s-Lock™ PLL technology, providing low-jitter, rock-solid digital stability.
• Input/Output: It features multiple stereo inputs, including balanced (XLR), unbalanced (RCA), and digital (AES3, S/PDIF, ADAT, TOSLINK). It supports up to three sets of stereo monitor speakers.
• Headphone Amp: Included are two high-current, audiophile-grade headphone amplifiers based on the Grace Design m902, with outputs located on the front panel.
• Control Interface: All controls (volume, mute, dim, input selection) are on the front panel, but it is compatible with an optional wired remote control unit (m904RCU).
• Calibration: The unit allows for precision calibration of inputs, outputs, and speaker levels, with a 100dB range in 0.5dB steps. [1, 2, 3, 4, 5]