I just have a quick question, I can't seem to find any threads on tube rolling on the Audio Ocean. I ordered a 12AU7 tube for it but have no idea how to replace the tube. Any tips?

Hey, I'm trying to get some better sound outta my M50x, I am torn between these amps. I like the HiFiman because it also has a DAC inside of it, but it is too expensive for me. I'm looking nearer to $100. I hear good things about all of them, but what would you guys think about it with the M50x...