If you want a setup for the HD800 I really liked the AnedioD2/Schiit Vali combination.  You could certainly substitute in another DAC or jump up to the Schiit Valhalla 2, which looks promising for dynamics headphones.  At this level just make sure not to skimp on the DAC as it can make a huge...

Try to figure out if it is one channel or both.  That would definitely make it easier to identify the problem

  I didn't really notice.  I have an extra pair of amperex I can send to you if you want.  Might be cheaper to snag them off ebay for $30-$40 though.

Raytheons are kind of harsh sounding in comparison with the Amperex gold pins.  Raytheons are more U shaped to me.  Bass is nice but the highs were too much for me.  Amperex has better transparency and a more neutral sound. Still trying to find some 417a's :p

  I believe that is the 2A3mk2.  The mk4 uses paralleled 2A3's instead of paralleled 45's for 6watt vs 3 watt...so MOAR powerz   I did briefly hear the HE6 from the mk4 at the Toronto meet but wasn't that impressed.  Hard to tell if it had the power to drive them as it had become quite loud...

I wouldn't worry about a dust cover.  Also from my experience you have the power supply WAY too close to the amp.  I am fairly certain if you move it away a couple of feet you will get better performance.

Just to be cleat the OPTs are the big output transformers that the back of the amp. We are talking about moving the power supply. You need to experiment with it but from my findings you need at least a couple feet of space from the power supply.  Other components will vary.  Just be warned that...

Feedback? There shouldn't be any noise whether music is playing or not. Make sure you have the power supply as far away from the amp as possible. The big OPTs on the mk4 need space from other electronics or else you will likely hear some noise

Interesting stuff and congrats on the amp buddy! Make sure you switch out those Raytheon's, the Amperex are much better. I am not entirely surprised the EMLs SP sound more forward.  How would you compare the other characteristics of the sound?

Fun contest...here are my guesses   53.9lbs 162.3lb 241.7lbs   Thanks for the chance!

  Glad you are enjoying it.  I see no real reason to go for anything else     Active circuit manipulation scares me.  Sounds like the Audioquest Diamond.   If you really wanted to spend that much I think you would be better off with something like the Offramp 5 and ShortBlock USB filter.

Sourcing 4 45s or 4 2A3s is an expensive and frustrating proposition.  The minimum it would cost you for 4 NOS 2A3s is $400.    The 2A3mk4 is also very large and heavy, which means shipping is expensive.  It cost me $350 to ship to Toronto and came in two boxes weighing 60lbs total.  I love my...

It is going to be somewhat system dependent, I did a test last weekend between another USB converter and the OR5 with my PWD. The results were quite similar.  There was a slight raspiness to some vocals that was cleared up with the OR5 and an increase in small details like vocal inflections...

Think of USB input as a transport.  Look for things like background blackness, clarity, resolution, dynamics.  Most of the effects of a USB implementation can be related to reducing jitter and filtering dirty computer power.  It isn't going to change the overall tonality or characteristics of...

2A3mk4 has better detail, imaging, soundstage than the BA that I have heard.  The BA is a warmer/lusher/more forward sound.  2A3mk4 also works far better with Orthos like the LCD3, HE5, Code-X.  Keep in mind that this is very relative.  They are all in the same ballpark.  Do I like the mk4...