[xerxe]

Thanks for the answers, Jakob!
I see you also use the U7's line-in for your piano, happy playing!
 
I am also thinking that I might need a headphone amp, but first I just want to see how the U7 manages with my T500s.
 
BTW, pietcux, all the amps that you mentioned are portable, and use rechargeable batteries. Is there no wall-pluggable (and perhaps not-too-expensive, like < $100) alternative?

 

[Jakob789521]

No problem xerxe,
 
Well I use a midi keyboard and a headphone out to for my piano, But that will soon be connected to the objective 2 amp.
And yes try out the amp on the U7 first, Mine gets loud but I want to avoid turning volume up in Kontakt.
 
Also I have been searching for something like you are, I didn't want portability, just quality.
That is where I found the Objective 2, JDS supplies the USA and Epiphany supplies the UK, But I got mine from a guy in the UK who builds them at a much higher quality and look to the other two company's.  
 
What is great about it is that it's meant to be plugged into the wall for full functionality, or it has two 9v batteries for portability (6.5x gain doesn't work on batteries but holy hell that would be loud) for 10+ hours battery life. So it's kinda like the best of both worlds. Check out the specs on it. I got mine for £85 delivered.
 
Im still trying to decide if my U7 or my headphones are faulty because I have never had semi audiophile equipment and don't know how it should sound :/ 

 

[pietcux]

You might want to check the Fiio E12. I have two of this amp. One is the standard the other is the limited edition. Both play well when pwered by usb and also last quite longon the Iinternal battery. And this amp has a lot of power.

 

[Jakob789521]

Oh I didn't realise you could use it while charging :/ I remember one not allowing you to do that. I think it was the E12

 

[pietcux]

No the E12 allows that perfectly. I practice that daily.

 

[Jakob789521]

Oh it must have been the E11 I think

 

[xerxe]

Ok, so I just picked up my Xonar U7. I can't wait to get home tonight and try it!
 
As for the amp, the O2 seems nice. This should be the next step, in a few weeks. Unfortunately I don't think I can find it in my country so that I can give it a listen. I'll try some local forums, maybe I can find a nice person who would allow me a listen.
 
Fiio E10 is another good idea, i think.
E11 is portable, and I don't really need portability, as I will only use it at home.
 
Thank you very much for your replies, guys!
I hope I can give something back to this community once I learn more.

 

[Jakob789521]

Nice it is very good, It's an all rounder for me  
 
Yes the O2 is excellent, Which country are you in? and it doesn't really change the sound, it's just a really good amp, I use the sound card to change the sound.
 
You would be surprised how small it is as well.
(That's what she said)

 

[xerxe]

I'm in Romania. There are plenty of hi-fi shops, but most of the wares are for studio, and less for home use.
For instance, a shop only had headphone amps with 4 or even 8 headphone outputs! That is a bit too much for me

 

[Jakob789521]

Hmm then it's probably worth buying from the UK and waiting a couple extra days, But see how your headphones work with the U7 first I only need the amp as I use a VST player that sucks when you turn it up haha.

 

[xerxe]

I finally installed it last night, and I'm very happy with it. It's driving very well my T500s, with the medium gain option (-6db). The sound is nice.
 
But the line in doesn't seem to be working. The thing is, if I stick in a microphone, it's working, but with the keyboard it's not. It doesn't detect that a jack is inside, and no sound is captured.
I'm starting to dig a bit, maybe I missed something.
 
L.E.: I also tried a guitar plugged directly in. As line in, I can't hear it. As microphone, I can hear it, but it's awfully amplified and cut off.

 

[Jakob789521]

That's great I have to use high gain for some reason, Think im gunna send it back for a replacement.
Are you plugging in the keyboard in the same usb slot as the U7? 
And are you selecting line in for the guitar?

 

[xerxe]

I think I solved the problem, and that it was my 1/4" to 1/8" adapter that was causing the problem. I just wiped the jack with my fingers.
Now I only need to figure out how to remove line-in latency. I'm not using any programs, just "Listen to this device" in sound properties.
 
Regarding the amping, I see the HD598 have 50 Ohm impedance. My phones have 40, and U7 is doing a good job driving them on medium gain. So, if high gain still isn't enough for you, then it might really be a faulty device.

 

[xerxe]

I found a workaround. Before I plug the mic in, I go to windows recording devices and disable U7 line-in. Conversely, when I plug in my keyboard, I re-enable line-in and disable the microphone.
I am happy with this workaround. I was thinking of returning the U7 before.

Now the only issue is the latency. Any idea how I can play my keyboard through the line-in without latency? Rather, with 40ms or less.
I think I do have ASIO, it came with the drivers, but I don't have ProTools, nor any other such software, although I might get one in the future. Are there other ways?

 

[Jakob789521]

Hey sometimes it can be the simplest things eh Im glad you found a workaround I gotta try it, as I have a mic aswell and cant stand the latency through playback so thanks. As for Asio, if you click on the 'Xonar U7 Audio Centre' at the top somewhere will be a button that Said 'ASIO', If you click that you can change the latency, I hope that works for you. 
 
As for my HD598, I have noticed the drivers rattling at really low base and High volumes
http://www.audiocheck.net/soundtests_headphones.php
If you activate bass checker does this do that to you also?
 
And I might try and return it soon, I think you may be right :/ it sais high gain is for >64ohms lol, thats a lot more.
Let me know how it works out
Regards
Jake