Tried the 12B4-A valves instead of the 6N6 and much preferred the result. The downside is the line stage now has no gain. However there seems to be less distortion and a more open presentation giving the impression that this version hasn’t as much sonic signature as the 6N6 version. The lower output impedance is able to drive the interconnects which are 4m long and power amplifier input much better. A little more detail here.

12B4-A Line Circuit

I’ve settled on a construction of “chassis in a sleeve”; the chassis made from plywood screwed together. It slides out the back intact. The design can change without the need to alter the sleeve. Sleeve is teak veneer over plywood. Front panel is Rimu veneer.

There is allowance for balanced inputs for the future but I don’t have any yet.