Hi Damir, No the DRD amps are a different project. These are my former WE91 with 6sj7 front ends. They sounded very good, terrific bass and very smooth. They just lacked a sense of dynamics that I could get even with my 1.5 watt DRD45’s With D3a installed the sound is a bit forward or bright, but not harsh and I seem to have lost some of my bass. I have the D3a biased at 1.9V at 155V at the plate. For a calculated 8.1ma As usual I have made the mistake of changing more than one thing at a time. These are not breadboards and require some effort to ‘work under the hood’ so wile I was in there I retaped for a lower B+ Moving forward, I may try to raise the current either go back to the higher B+ or try to scare up the appropriate PS dropping resistor. (How come I never have the one I need on hand?) I do have a pair of 6688a’s on order (closest I could find to the E180F from a US source, with out looking too hard.)…John