dcevans,
sorry I wasn't around yesterday to answer your tube questions. So, here goes: first, a question, do you have the most recent Dynamo or the original? I have owned both. The original Dynamo is a sweeter sounding amp though less robust in power supply. The original uses 5U4G rectification or equivalent and the newer model 5AR4/GZ34 or equivalent.
My original Dynamo SE sound best with Gold Lion KT-77s; they were compared to Psvane black 6CA7-Z (el34) which I used initially for about 6 months. Then I conducted a tube shootout. NOS Siemens el34, Tung-Sol el34s, New Mullard el34s and Gold Lion KT-77s. My results matched reviewer Steve Smith's results closely. Order of finish: KT-77s Psvane, Tung-Sol, Mullard, NOS Siemens.
My 6SL7 choice is either RCA Red base 5691 or NOS Sylvania 6SL7WGT. Rectifier tube best NOS GEC 5U4G, NOS Mullard CV378, RCA 5U4G or NOS Mullard 5AR4.
Along the way I modified my original Coincident Dynamo SE at the advice of Yazaki-San. Read about this gentleman on Jeff Day's Blog now on Positive-Feedback. Yazaki-san recommendations included strengthening the power supply, use of better capacitors, NOS resistors, rewire of internal wires with Old Western Electric tin-plated copper.
You might consider contacting fellow Agon member grannyring for a loom of Dueland powecords, interconnects, speaker wire...all of which work great with the Coincident and my current Tekton speakers, Lore and Mini-Lore. I also use these wires with my DeVore Orangutan 0/96 Leben. Best, mikirob