I suggest you go a different route, along with freediver`s suggestion.
Replace your preamp with the Rogue RH-5 headphone/preamp. Go the headphone route. The Rogue does this, while maintaining the tube pre part, on your main system.
I have found that many old rock recordings sound better over a headphone system.
Then, replace the stock tubes in the Rogue. I think they`re JJ`s. Get the reissues of Tung-Sols or Gold Lions. Then, eventually, do old stock tubes to your liking.