Need help C-J monoblock LP-140M with Siemens CCa

How long have you had the NOS/NIB Siemens tubes in your CJ LP-140Ms? Did you just install them and they started going bad a few days after you installed them? Did you follow CJ's tube bias directions to make sure you installed the tubes with the right bias setting? I hope you installed them without touching the tubes with your naked hand (should always use a cloth or gloves etc) as the oil on your hands when in contact with the tube glass can make them "pop" and go bad. I would call CJ for proper tube installation and bias settings for your mono blocks. With some of your tubes going bad you may have also blown some resistors in the circuit boards, so if your dealer has a technician who is familiar with CJ gear check your amps out to make sure it is only the tubes that need replacement that would be your best path forward. Good luck.

Sorry..I misunderstood. It's the input/driver tubes that went bad not your power output tubes. So the answer is there is no bias adjustment for input/driver tubes. The bias setting is for the output tubes. Then replacing the 6922s is relatively simple and is a matter of trying out different variants to see what you like best. Good luck.

Vinhusc...have you heard the amps with the stock CJ 6922s? If not, I would at the very least do that before deciding to switch your amps and see whether you like them or not.