I mentioned Amperex Organge Globes because they seem to be out there, are not the priciest, and are a reasonable representative of what early (NOS or near NOS) tubes can do. But there is a variety of manufacturers: Telefunken, Siemans, Mullard, etc. You don't need all ten of the same manufacturer , but they must all be of the same type (6DJ8, 6922 or 7308). I've found that mixing manufacturers can yield the best results. I'm guessing that two or three per channel would make an improvement.
So what do less than contemporary tubes bring? Typically more extended highs, much better harmonics, and often a deeper more dimensional souundstage. Their sound tends to be less 'mechanical' or analytic - but I don't want to over-generalize. And NOS usually will last quite a bit longer. That was certainly the case with my 16LS. There simply was no point listening to the stock CJ 6922s (typically Sovtek) when there were easily better choices. Price is all over the map - anywhere from $35 a tube up to several hundred. Depends on the seller and the tube.
Tube rolling is one thing I miss w/ the ACT2.
Tim