I have X250.5 & replaced with Nuforce Ref9SE V2 , it actually sound better than my Passlab in my system. I took my Nuforce to compare with a big Krell, wow my friends were amazed how good they sound in his system. I am looking for a match tube preamp for my Nuforce, I was told on the phone class D amp are just toys by a local audiophile store after 20mins with him, he told me to come to the store and listen to their reference system. And that is what music sounds like. So i took my Nuforce down to him, we sat down and listen to his system, wow it did sound better than my system. Then another 10mins on class D toys lecture, he finally agree to put on my Nuforce. After 10 mins music on cd, we have 2 hrs of music on his Lp collection. He acually apologize for what a hard he was before , that tell you how good it sound in his system.