What tubes for ARC LS 5 preamp - 6922/6DJ8

Hi,

I'm a neophyte as far as tube rolling goes
I have an ARC LS 5 preamp which has 10 6922/6DJ8 tubes

I currently have the Soltek 6922 Russian tubes that Arc stocks in their units

can anyone recommend a tube or combinations of tubes to achieve warmth, transparency, tonal balance, richness etc.
(less transistor like - more musicality)

probably not looking at the ultra expensive, but the best bang for the buck a step or two above the stock solteks

also can anyone recommend an online vendor or audiogon member who sells quality tubes at reasonable rates

thanks a lot

Tom