Congrats! They were my first audiophile grade headphone as well and they certainly blew me away.
They are very efficient headphones, though. I used to have a Vali that I used with my K550, but I couldn't handle the microphonics. If you touch the Vali at all with the K550 plugged in, you'll hear tube ringing for quite a while. It can even be bothersome on very quiet recordings, even with the Vali totally still. I would recommend the Magni over the Vali for sure. If you want to get tube sound through the K550, you might have to look elsewhere. I can say that Modi/Magni/K550 is an incredible step up in clarity over PC audio.
Thanks for the advice! The magni was my first choice until I was intrigued by the tube sound as I prefer tube amps for instruments. I shall begin with the magni and explore tubes down the road.
That said, the headphones already blow my gaming headset out of the water...I'm excited to see what the addition of the schiit stack does for them!