Tennis, I'd leave any KT88 changes for last (if at all). Now if what you're after is slow and syrupy (we say 'schmaltzy' in my neighboorhood ;--) I think you can't do better than NOS Mullard 12AX7's (the UK ones, not the Holland ones). And if you like what they do in the AX spots, and I think you will, I have 2 matched pair of Mullard 12AT7's I'd be willing to offer you. I don't have any Mullard 12AX7's unfortunately, or I'd let you try a set.
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