Used amd in good working order Engl e530 Tube Preamp, Modern Rock, Guitar Preamp.  Power Cord included.  There are some rack install marks and screw marks, but it was safely used in rack box setup.  It gives you options on how you want to use it or route signals.

It’s hard to believe what you can fit into just one height unit! The E530 Tube Preamp has four channels, because the Clean and Lead channels each have a Lo and Hi-Gain option. Each channel has its own tone control, and the lead channel even has two mid-range controls (Lo Mid and Hi Mid). The miniature, 1.5-watt power amplifier allows you to get started right away. Practice, record and play with headphones on the fly – without the need for an additional power amp! For “real” volumes, the stereo output is used, and even the recording out is stereo. The output level can be increased by up to 15 dB if required. The sounds are all made in this rack center!

https://www.engl-amps.com/shop/rackmount/modern-rock-preamp-e530/