This is the Objective-Interim Amp Mk2Mod2. As you can see it'll drive a K1000 with little effort, though ideally I should be using the 6BL7 tubes on the output and setting the bias & voltage to match. Which can be done with some switches which you can't see in the picture.
Schematics & notes on this page for the Mark2Mod0 version. Tyll said it sounded good, and as the not so impartial designer & builder, I have to agree.