BAT VK-31SE Tube Preamplifier History: 1. Serial number shown on back of unit. Believe it was manufactured ~ '03, '04. Contact BAT to confirm. 2. I am 3rd owner since April 2010. Previous owners either lost employment and/or down sized. 3. I have never had in to BAT for service due to any issues.Tubes have never been replaced as I very seldomed used in my separate 2-channel system. Reason for Listing for Sell: 1. Marantz 7702 mk ii is my go to for both HT and 2-channel listening. Prior to Marantz, Anthem AVM PrePro did all the work.