Kzhtoo,
You could also just get a new preamp with HT passthru. I think tubed preamps paired with ss amps offers better results than all ss. I use a VTL 2.5 tube preamp with HT passthru with a ss amp and it not only improved 2-channel performance dramatically, it subtley improved HT sonic performance, too.
A properly selected tubed preamp with HT pass could do the same for you, with the added benefit of better 2-channel performance. Sorry, I'm not knowledgable enough to offer a good tubed preamp match with your excellent Pass amp but I'm sure some other members are.
Just an alternative to consider. Good luck.