Slovakia JJ ECC 802 and 803 tubes.

Currently my preamp has less than 50 hours so I'd like to put some break in time before re-tubing. I had a Gold Lion 6922 tube in my former CJ ET3 SE and liked it very much. Being the preamp uses both 12ax & 12au tubes should I stick w/the same brand for both??

As you can see, these JJ variants feature long plates.  That's the rationale behind JJ providing different designations, which they have done with some of their other products.  At the time they wanted folks to take notice of these new tubes, and their potential for different sound.

Maybe that's not completely obvious, but they offer a more different sound than the typical 12AX7 and 12AU7 offerings.  In general, I've found that short plates produce a tighter, punchier, more focused sound and vice versa.  That's not to say it relates to brightness or harshness, as the better variants stay far away from those attributes.

If you do want to experiment in the future, give the Shuguang (or Psvane) triple mica 12AX7 a listen.  They're about $10, and compete with the very best ever.  You'll hear quite a bit of difference, and begin to determine how to best steer your amplifier to your tastes

Shuguang 12AX7LS black tubes from Grant Fidelity are superb. Not cheap. Good from the start, they need about 20 hours to sound right and improve up to 50 hours. I think they outshine Telefunkens.

Thanks for your input on Shuguang and Psvane tubes. They were not on my radar. The CL-38 SE is sounding very sweet w/the current tubes but after more break in I'm going to look into these tubes.