[gatorjon]

First of all, I have read this forum for a few weeks and feel that the people here are incredible knowledgeable with top-notch advice. Therefore, in my first attempt at building a headphone system, I seek your advice because I have reached an impasse. 
 
 
Here is the current equipment I have now: DT770pro 250, DT1350, Aune T1 (eh6922).
I have given everything at least 40 hours of burn in. 
 
I listen to a mixture of loss-less, high and low bitrate mp3, and spotify. 
I listen to every genre of music. In any given day I will go between indie acoustic, mainstream acoustic (ie mumford&sons), blues, orchestral, dubstep, hard-core death metal, power metal, country (new and old), blue grass, electronic, folk, classic rock, and hip-hop.
 
Here are my requirements:
-Must be closed- for office use
-Bass quality is much more important to me than quantity
-No sharp treble ie. sibilant type sounds. Which probably means the system must be more tolerant of some of the more low-quality sources I listen to. 
-Price is a factor, would like to keep the phones under $225 and the DAC and AMP or combo DAC/AMP under $300
-Have no preference for over/on ear. Tube vs solid, or portability. 
 
Here is what I have found with the current setup:
-DT770, Bass- a lot but I can live with it, Mids- far to recessed, Highs- Cannot stand them, way to harsh and sibilant (with both high and low quality sources). Love the soundstage
-DT1350. Bass- what they lack in quantity they make up for in quality, Mids- too forward, very bothersome to my ears, any track with a piano drives me nuts. Highs- not sibilant at all, sounds very pleasant. Comfort not a factor. Would prefer a larger sound stage but not a deal breaker. 
-Aune T1- have no other comparison. May or may not be part of the problem or solution. 
 
So, I am looking for something that solves the treble problem of the dt770s and the mids problem of the dt1350. If changing components could make either of these two phones fit my preferences or if the T1 would fit any of the phones below, I am very open to that as well. 
 
I have done significant research on this site and others and have loaded up a cart on Amazon based on that research with the intent of trying the various combinations. I would really rather not spend that much money and have to deal with all the returns. Therefore I am asking you all to help me narrow down my choices. Here is the equipment I am considering:
 
Phones:
-Shure 840's
-HD380
-DT250 250ohms
-ATHESW9A
-ATH-A900x
-HD25 II
 
DAC
-Audioengine D1 (also an amp)
-Audioquest Dragonfly V1.0
 
Amps
-Bravo Ocean 
-Little Dot Mk II
-Schitt Vali
 
 
Thank you in advance for your advice 

 

[PurpleAngel]

I do like the sound of my ATH-A900X and adding the Hifiman Velour ear pads makes them easier to wear.

 

[gatorjon]

I forgot to add the most important part: 
 
Please give me any suggestions for combinations of equipment that I may have overlooked.
 
I am even open to having to mod (ie T50RP) in order to get the best sound. I will have to draw the line at anything requiring soldering because I would have no idea what I was doing and would probably ruin whatever I was working on. 

 

[gatorjon]

  I do like the sound of my ATH-A900X and adding the Hifiman Velour ear pads makes them easier to wear.

How do you compare the sound of the A900x to the DT770? Do you amp them? If so, with what?

 

[PurpleAngel]

  How do you compare the sound of the A900x to the DT770? Do you amp them? If so, with what?

I do prefer the A900Xs over the DT770s, I guess the A900X has a more balanced sound.
Normally I use an Audio-GD NFB-15.32 ($300) external DAC/Amp for driving my headphones while at my Win 8.1 PC.

 

[Trunks159]

Id recommend the ES FC300. It has an authoritative bass that is extremely tight. It also extends reaaaally low, even lower than the momentum.

Its mids are great, and the treble actually has presence, but no sibilance here.

The soundstage while not as large as the DT770 or A900x is still large.

Other cans:
ATH WS99
Focal Spirit One