Looking for Raytheon 5751 (windmill getter)tubes i spotted ones labeled JRP-5751 W1 instead of the CK 5751 i used to see. Anyone knows what means the JRP/CK prefix? Should i expect a different valve?

I recently got a Ear+HD from the good Dr. Lloyd looking for the famous sinergy with the RS1s and i'm really loving it. Now i feel like moving forward from my CDP and soundcard and getting a dedicated DAC from the same league to the chain. I'll be mainly focused on USB then Optical, not...