6J2 tube rolling?


If I have a tube phono preamp with 6J2’s from the factory what would I try if I wanted to roll them to something better? A better brand 6J2? If so, which? 

Another tube all together? If so, which? 
128x128dougeyjones
not knowing your budget, I hopped about on eBay, see what's interesting,

this unit is very simple appearance, but read the notes, very versatile for MM, MC HO, MC LO
you would be set for most future cartridge choices

https://www.ebay.com/itm/Jolida-JD9-II-Tube-MM-MC-Phono-Preamplifier-JD-9-Mk-2/333673949970?hash=item4db0846b12:g:SUAAAOSwXvZfJz7V

Jolida site

https://www.jolida.com/product/jd-9-ii-phono-preamp

different tubes I know, just think they are worth considering, if only to spark questions
How’d we get from replacement tubes for a cheap side project to $500 tube phono pre’s 😂