Just signed up for the upcoming anax 3.0 mod. Just wondering is there any cons to the anax 2/3 mod ?

Jeff, your perception of the HD800 is very dependent on what you plug them into.  It's a serious commitment to the transducers capabilities.  If you aren't willing to go 'all in' in the neighborhood of 1-2K worth of upstream gear, I'd say avoid it or save up.  I had to live w/ the HD800 from a DACPort for 4 months while the Super 7 was being developed and built.  That is to say, I never listened to them and everytime I tried they were just like the critics say.  But I was fine with this having heard the 800 from the DACPort, Super7 and WA5 at a meet.

The 800 sounded just as bad as all the stories when I first heard them at the meet using my DACPort.  Then I met Craig and plugged them into the Super7 once the crowd dispersed and did a 'wooaahh'.  Then found a maxed out WA5 that purrin hooked his PWD into and did another 'wooaahh'!  I was in planar camp at the time w/ the T50rp and LCD2.  It was after that I did some audio calculus and felt the 800 was the best for me once I felt I had the transducer figured out based on actual experience.  It was the last thing I ever wanted to do, build a whole system around one phone.  Insane!  So I went all in and bought the HD800 and looked at them sitting there for 4 months because they were about as enjoyable as rice cakes.

Treble.  If you listen medium to low volume, you won't have a problem.  That is unless your gear fails to deliver the bass and dynamics to prevent you from cranking up the volume to flatten out the FR.  Hoe that helps.

I too have been vaccillating over whether or not to go down the HD 800 path. My first encounter with them was "OMFG these things are SOOOO bright and abnormally spacey sounding!" After repeated listenings whenever I've gone down to the headphone store, they gradually started to grow on me. But I still found them too glarey/prickly with certain tracks/genres. I finally decided I'd bloody well make the mod materials and try them out. So I found some 2mm kiddie-crafty foam and shelf/rug liner-type material (I don't know if it's as thick the stuff Marv/Mike used - being in Taiwan I takes what I's can gets) and had some felty type stuff leftover from my K7XX mod attempt.

Upstream gear:

• iFi iDAC2 (I know, I know), I usually take  my micro iDSD which sounds the same to me (and better than the nano) 
  
• Note 3 playing 16/44.1 FLAC
  

I made the innerfidelity Omega foam/felt sandwich as per Tyll (like on the floor)'s instructions and popped it in under the dust cover (no adhesive, it more or less stayed in position). The highs were tamed a bit, but not nearly enough. I then popped the shelf/rug liner donuts on top of Tyll's Omegas. Better. Still a touch glarey. I had to play them pretty loud in the store environment so that probably didn't help either. I listened to the HD 600 while I was there and the bass was too woolly and highs rolled off in comparison.

The clarity/soundstage of the HD 800s is very appealing, but I couldn't use them for all my music with the gear I have now and the mod as above. I guess more can be done tweaking the mod as I'm willing to sacrifice some stage/clarity for reduced glare and increased bass. Perhaps the nastiness I'm hearing is actually what's there in the recording (notwithstanding upstream gear contributions), and the HD 800 is revealing it.

My setup has to be semi-portable (and affordable), so going from the Best Amps for thread, the best I could do would be a Schiit Vali/Valhalla2 that I could plunk on the coffee table next to my laptop and micro iDSD.

I really enjoy my ZMF Blackwood which I'd like to leave at the office and am debating between the HD 800, ZMF Omni or both for home. Comments, suggestions, iFi abuse are all welcome 

Today I had my iDAC2. In order to use my own tunes, consistency, and reduce variables, I usually try and run everything off of my Note 3 + micro iDSD stack. I realize that this might not give the optimum sound for amp dependent phones, but when I was shopping around for a portable DAC/amp, with "easier to drive" phones, I couldn't hear much difference between them, desktop units like the Oppo HA-1, and directly out of my Note 3. I definitely heard a difference with the HD 800 (I think I plugged them into my phone just for laughs).

Spending a ton of $ on an amp just for the HD 800 is not feasible for me. If I could tweak it so it didn't make me wince every now and then, I think I wouldn't mind having one. I could probably live with converting it from the audio microscope that it is to just a half-decent magnifying glass, since my ears probably aren't good enough to see the difference.

You could always get a pair and poke around with your own mods, but I really can't stress enough how much you'll want to save for a really nice tube amp to pair with it down the road. It will literally change your life and make you a healthier, more optimistic person for the rest of your life. Maybe a slight exaggeration.

There's a Schiit dealer in Taipei and I called down to check if they have the Vali and Valhalla2, which they did. Brought my micro iDSD this time. The Vali didn't sound much different to me than the micro's amp. At first I thought the V2 toned downed the highs a bit (I think there was better stage too, but I wasn't trying to listen for that). Dude turned me down when I asked if I could put the mods in, but I popped in Tyll's Omegas when nobody was looking. The effect was much better than what I remember from yesterday. I didn't put the rug liner in as they're too fiddly, but out of both the micro and the V2, a couple of problem tracks were almost listenable with just Anax Mod 1.innerfidelity. And comparing high/low freq response between the V2 and micro (with mod in), in the end I couldn't hear any difference in the highs and actually found the micro to have more bass.

This makes me more optimistic about starting down the HD 800 path. I seems like I should be able to get them to an OK state with the gear I have, and then look for the right amp to "change my life and make me a healthier, [even] more optimistic person." Next time, I'll bring both my micro iDSD and iDAC2 to verify that the iDAC2 sounds more glary/prickly, and test the micro iDSD with Anax Mod 2.innerfidelity.

Incidentally (and completely OT), they just got the Rag and Yggy in. I asked if they'd let the Yggy warm up for a week or at least left it plugged in and got a weird look back. Then it turned out the Rag already had an owner who came in to pick it up. They actually put on white gloves to box it up