I found the following information online at Deforest. Com. Designed to pair up with Deforest’s DT-700 radiohome receiver, this two-stage amplifier comes in a walnut cabinet identical in size and shape to that of the DT-700, with audio inputs positioned to correspond with the audio outputs of the radiohome. The connection diagram on the inside of the lid details how the two components are to be connected to each other and to the battery supplies. The instructions inside the lid actually say that this amplifier can be used with any type or make of radio receiving set. This amplifier is in IMMACUALTE condition. The black Bakelite panel looks great with only a small minor imperfection underneath and to the right of the right tube. The nickel plated hardware is free of rust and corrosion. The walnut finish is beautiful and the cabinet is nice and solid. The latches work perfectly. The interior is super clean. This piece measures approximately 9 5/8″ by 8 1/2″ by 7. Please be sure to check out our other auctions as we have several other EARLY DeForest pieces including a W5 radio w/ speaker and a W6 Speaker!! We have not tested it in any way. We can be reached at 317.340.6170. The item “VTG (1922) DeForest DT-800 Two Stage Amplifier RARE Marconia Era Radio” is in sale since Tuesday, June 21, 2016. This item is in the category “Collectibles\Radio, Phonograph, TV, Phone\Radios\Tube Radios\Pre-1930″. The seller is “2brosvintagestuff” and is located in Pittsboro, Indiana. This item can be shipped worldwide.