I guess different voltages on R3/R4 and R5/R6 are a prove that something is wrong in the circuit. Am I right? These voltages were measured with desoldered lm317 and lm337. Voltages are different also on the inputs of lm's. I'm waiting for rectifier diodes and filter capacitors to change them -...

Everything is grounded well and hum is still there. Nevermind, I'll try to do something with it.  

Lm317 was dead. Now all works. I had some problems with a huge offset (about 200mV) on the output, but I've reduced it with a trimpot to about 10mV. Now the most annoying thing is hum. It's quite loud and in my opinion its caused by a pot and resistors (poor chinese quality like all parts - a...

No, it worked before resoldering the power section.

Maybe someone can help me. I've bought a kit, soldered it, then turn it on and... it works. But. A DC offset on output was about 200mV on a first channel, and 5V on the second channel. I've checked opamps Vcc and it also wasn't correct. So i've resoldered a "power" section of the BCL and there...