It's BBE's excellent Sonic Maximizer and a DI all in one box. Handy for acoustic stuff, designed to restore all the missing frequency data you lose in a normal signal chain and speaker. 

Model: BBE DI-100 Active DI & Sonic Maximizer
Made: USA, recent model
Serial: N/A
Type: pre-amp/DI
Power Input: standard 9v DC centre-negative supply (not included)
Accessories: original huge box, manual

Condition notes: used, no major marks. Tested and fully functional.
Overall: excellent condition (9/10)