No, they are two Valve Art KT66s (and JJ 12AX7 and JJ GZ34), all with a plastic base. I'm waiting for the new Valve Art KT66 to arrive, I will test  them next weekend.

It works! It sounds! 

Though cathode current is like 10 times lower it should, right now (maximum 4.6mA!). Is it possible to be because I connected a 4 ohm speaker to the 8 ohm output?

I'll try tomorrow with the 8 ohm load. I connected the 4 ohm speaker because that would drop the energy efficiency, so it doesn't sound too loud for 11PM. And also because I didn't wanna risk my scumback speakers if something was wrong.

If tomorrow, with a matched load, the cathode current is still that low, should I use a bigger bias pot? (I'm using a 25K bias pot).

The small current cathode must be happening too because I'm using a lightbulb  current limiter, that drops B+ Voltage from 400 to about 300 right now. I'm still using the lightbulb limiter because, though everything seems OK, I've realized I haven't got slow blow fuses but fast ones.

It was the lightbulb resistor. I'm reading the neccesary 40-45mA adjusting the bias pot. I just risked it, uninstalled the  lightbulb limiter, put a 4 Amp Fast Blow HT Fuse instead a 2Amp Fast Blow HT Fuse (because I haven't found Slow Blow fuses around here yet) and it just works fine. Well, fine is not the word, IT ROCKS!

Thanks for your help, really! I'll submit a video to youtube soon.