Out of curiosity, were the Sovteks indeed the 12AX7LPS? Typically the LPS sounds as smooth or smoother than JJ 12AX7s and is very quiet unless you put 'em in a high powered combo amp and crank it up, because those looooong plates will resonate.

OTOH, the Sovtek 12AX7 WA and WB are just as you described, grainy, harsh, and noisy. JJ 'AX7's will slaughter 'em. If I'm not mistaken, one of those is the stock preamp tube in the 5150 nowadays, or else they used to be.

Thermionic