Hi,
To answer your questions:
1 - Are
all the tubes socketed or are any of them soldered directly to the PCB?
Yes. All socketed.
2 - In this amp is the 6U8A a direct drop-in replacement for the ECF82?
Yes. Some of the staff personally use the 6U8A, the RCA in particular are nice.
3 - Can the amp operate with regular EL84 tubes as opposed to the EL84X tubes that come with the amp?
Yes it can. BUT please ensure they are 100% EL84 (not the often inferior spec "almost EL84" from Russia and China) and remove the Jumpers on the PCB that need to be fitted for the EL84X.
Tube rolling will invalidate the warranty. So please wait after 1 year before changing the tubes. We really hunted high and low for these tubes and they are not to be scoffed at.
4 - Are the cabinets solid bamboo, bamboo veneer, vinyl veneer or something else?
They are solid bamboo, except the baffle which is solid bamboo additionally reinforced with a layer of MDF, to allow screws to "bite" better and to give extra strength to the baffle which is weakened by the driver cutouts.
Plus, we were notified today that Audio magazine (Germany) that the Retro full system was awarded "Reference Class" which places the Retro in very esteemed company indeed, not least given other Reference class products cost a lot more. Audio is pretty well-regarded and in Germay, they are very thorough.
As soon as we have a translation, we'll drop it in here.
Cheers.