Tubes in the preamp's power supply -how important?

I have EL84 and EF86 tubes used in separated power supply module of the line/phono tube preamplifier.

Stock tubes are Sovtek EL84 and Electro-Harmonix EF86.

I am curious how important is the tubes quality in such application. Is there any reason to change tubes to some NOS – Telefunkens for example?

How important these tubes are in power supply?
If change – what tubes do you recommend?
Depends on the design of the unit. In Audio Research, Aesthetix and Allnic, three that I have experimented with, the effect is huge.
Huge indeed. My experience reflects the same with Aesthetix and even more so with the Counterpoint and Aria products. I recently replaced a Sovtek EL84 in a rebuilt Counterpoint SA-2 with a Valvo EL84 and was mightily impressed with the added smoothness in the mids and greater tonal coherency on the top. Surprisingly, the Telefunken EL84 was rather dull here. It pays to try a few different brands to determine which one "locks in" for you.
Yes, agree with the above posters. They make a big difference. Try the NOS varieties and go fro there. All sound different and one will suite your system best.