Lefson Repair - BOSE-4401 - Solid State Four Channel Preamplifier. Year 1975. We replaced some components, the 4 gang volume potentiometer, and cleaned some contacts. https://www.lefson.com/fr/reparation.php | Facebook
4401 - Bose 4401 - Audiofanzine
Rare Bose 4401 - Solid State Four Channel Preamplifier - Catawiki