I am sorry, I did not mean to ask for a competitor to RMA, I really like the DAC part of it.  I was hoping for a complementary product to the RME.

Have you tried the different options in the DA-filter settings?
Those might make a bigger difference than another amp.

See manual page 21 and 57, but just listen, don't look at the curves before hearing.
Take notes what you like about each filter.

Next:
Try the Polarity / Both- vs. Off-setting (manual page 21).
Depending on the headphone it can make a big difference in the bass reproduction.

I know, it shouldn't make any difference at all, as humans are said not to be able to hear the absolute phase.
In fact, as it's so easy to try, I found that it makes a significant difference.

As recording engineer I know that we are usually doing the same kind of polarity settings for certain instruments.
Most common e.g, the bass drum's first pulse goes positive with most used microphone techniques.

I'd like this chance to remind, the RME is a swiss knife and everyone has a different taste.. so, since we are on it, why not try to take advantage of the so many options in this device?

So in my most humble and ignorant opinion once you get the signal as transparently as possible from the source (this DAC does that and I think it also does that in the headphone amp section), and once the headphone amp is as "powerful" as you may need for all sorts of headphones.. all that it takes for you to adjust to your needs are the:

* Parametric EQ
+
* Bass / Treble section.
+
* Loudness to adjust bass/treble at diferent volumes.

And save setting for each headphones... no?

--

One example, one day a friend and I went shopping to a hifi store which had a headphone amp and lots and lots of good/better/awesome headphones to try.

Each time we were using the same device, just trying different headphones... the AKG sounded flat, the Grado sounded "complete", the Sennheiser HDxxxx sounded warm, the Focal Clear sounded extremely detailed and so on... Also my friend prefers a more superflat sound and I like precise but still a bit more "bassy".
TLDR: different headphones, different sound,  different tastests.. one transparent powerful dac+amp to rule them all!

Yawn....Zzzzzzz

We all need to be careful with this "Neutrality" BS.   In reality, We audio types don't have the faintest idea of what the Performer ACTUALLY sounded like in the Recording,.Mixing, Mastering Sessions.   We tend to rely more upon dreamy "HiFi" ideals" that quite likely never truly existed.  Have you ever listened to a Steely Dan Album?   

Chocolatey Vocals...Honey-Like Strings..., etc. it's all Bull, and just ONCE in front of Live, Unamplified Music would convince you of this.   How few seem to be aware that the SAME instrument can sound suprisingly different in the hands of two different musicians, yet they're BOTH right.  Now what?   An Audiophile Dichotomy! 

Which device makes the Musicians sound more like I WISH they did??   Does anyone else see the lunacy of this?  Using a similar Logic, it seems any of us could be a World Class Violinist by merely OWNING a Stradivarius! 

RME does it's part to cut through the nonsense by striving for a device that simply outputs a very linear facsimile of it's input.  Nothing more or less.   

It could be that if your Trebles "fall apart" you are realizing for the first time ever that the "Hi-Hat", and Snare Drum in your records were in fact created by Noise Gates...not an actual drum kit.  Surprise!!! 

So there's my take on the nonsense.  It took me a LONG time, and MANY foolishly spent dollars to arrive at these views.

Curt

There is a whole world between "very efficient phones" and LCD-4

I tried to clean up this unfortunate thread as good as possible. Please everyone stay on topic.

Hello, Zeus,

Headphone out of the RME is one of the best you can find on a DAC.

I use the Bryston BHA-1 with RME ADI 2 DAC Fs. Headphones (Sennheiser HD800 & Beyerdynamic DT990)
In my opinion it sounds slightly more open and natural in the présentation than the direct headphone out of the card.
This is when using XLR input on the Bryston and its clearly perceptible.

I'm wondering if the problem is not the Hifiman being naturally bright (maybe a change of the pads could help)
You have plenty of equalization possible with the RME and considering the price of a good headphone amp you should try some adjustments before purchasing.
I listened recently to the Hifiman Arya on my setup and it was very good. No experience with the Ananda. And the fostex sound have too much bass for me (I tried a TH900 on the Bryston)
If you go that way I will recommend something like Bryston or Violectric HPA V281.

Best regards

Have you looked into trying different cables on your headphones and USB connection?  I'm using Hifiman Arya's with an ADI-2 Pro FS and discovered that my standard computer USB cable with built-in ferrite bead was strangling the sound.  When I swapped it out for a Supra USB 2.0 everything became warmer and richer.

Perhaps ask a good dealer about headphone cable options and he/she should be able to direct you to 'warmer' cables and might allow you try them out in the shop.

And even with those components, the "cable sound" wouldn't have been changed, as it is not audio signal in a USB cable, but data...

I've tried to print a sad letter with a cheerful color USB cable, the printed letter was still sad...

I love DarkVoice, does everything tube amp should aka makes low quality audio sound listenable and it's <300$, I use it for playing retro games.
If you just want more warmth learn how to use the eq on your RME