Weber Copper Cap WX5 for Audio Note?


Have anyone of you used a Weber Copper Cap WX5 in an Audio Note equipment? Do you think it is safe to use as a replacement for 6x5 tube in Audio Note M2 Phono Balanced preamplifier?
I'm not sure if the short warm-up time of copper cap is OK for the AN. The 6x5 tube warm-up takes about 30sec I guess.

Kind regards,