I am away to school next year and need a new headphone amp to take with me. I currently have a set of high end KEF speakers hooked up to a Denon receiver and use the headphone output on that with an HRT Music Streamer II DAC to drive my headphones. It has this annoying hum when nothing is playing through the headphones that it doesn't have if I'm using the speakers. Would this be eliminated if I use a dedicated headphone amplifier?
I currently have the Beyerdynamic DT 990 600 Ohm, the Beyerdynamic Custom One Pro (16 Ohm) and the Sennheiser HD 558 (50 Ohm and modded to remove the excess foam) and want the amp I get to work with all of them. It's especially important that it works with the Custom One Pros because those are what I will likely be bringing away with me.
I was eyeing the Schiit Valhalla because it looks cool and is supposed to be great with high impedance headphones but it's a bit more than I was hoping to spend and I don't like how it doesn't have a pre-out. How bad is it with low impedance headphones? Is having to buy tube replacements annoying? It just seems like an added expense.
The Schiit Asgard 2 seems to be the best option for what I need. Would you agree? How well would it work with the headphones I have? Does the passthrough RCA degrade audio quality at all if I decide to hookup a pair of speakers eventually?
Lastly, is the DAC I have good enough for now or would you recommend a higher end DAC to go with the headphone amp?
Thanks for taking the time to read this, I really appreciate it!