[alanriedi]

I'm using the HD598 headphones with a Xonar D2 soundcard. It sounds good to me.
How much a FiiO E7 for example would improve the audio quality ?

 

[Head Injury]

The D2 is a very capable sound card, and with high impedance headphone you won't find any improvement with much of anything.
 
However, it apparently has a high output impedance (probably 10.7 ohms like the Essence series). That's causing havoc with your bass, because the HD598 is very picky about output impedance. If you switch to a Fiio E7 you should notice a drop in bass centered around 90Hz, with a smaller drop as you get further from 90Hz, down to about 20Hz and up to about 400Hz.
 
The result would probably be a clearer sound especially in the low mid-range, but less bass volume and impact.

 

[skydogis]

I just wanted to add that Headinjury is right as i realised today connecting my Xonar D2/PM with Fiio E7 and trying out if there is any quality difference between the duo and the Xonar solo with Sennys HD598. There IS a clearer low-end with the line-out to E7 setup other than the far greater achievable volume comparable to the Xonar driving the HD598s. Allthough the ideal would be line-out to Fiio E9 or equal tube or solid state amp from what i get from my listening experience and the forums i 've visited.

 

[Head Injury]

Quote:

I just wanted to add that Headinjury is right as i realised today connecting my Xonar D2/PM with Fiio E7 and trying out if there is any quality difference between the duo and the Xonar solo with Sennys HD598. There IS a clearer low-end with the line-out to E7 setup other than the far greater achievable volume comparable to the Xonar driving the HD598s. Allthough the ideal would be line-out to Fiio E9 or equal tube or solid state amp from what i get from my listening experience and the forums i 've visited.

If the problem with the D2 was output impedance, the E9 will have the same problem. If you need more volume, make sure to get something with low output impedance.

 

[skydogis]

I am completely satisfied with the volume i get with the E7, as the HD598 aren't that hard to drive. I just wish the D2 had a dedicated headphone amplifier just like your STX able to drive the HD598 lood and without the low-end overpowering/mufling, considering you can select/switch the headphone impendance in the STX or so i've understood from what i ve read. Thus i would'nt have to jack a second amp(E7) in the front lineout jack of the soundcard like i do now, allthough i am not sure i am missing, theoretically, anything in quality by doing so, apart from the obvious gain in clarity and definition on the low-end because of the correct impendance of the E7. Perhaps i'll save up and get an STX or whatever comes up at the time and suits my head-fi needs. Thanks for sharing your thoughts though.

 

[Head Injury]

Quote:

I am completely satisfied with the volume i get with the E7, as the HD598 aren't that hard to drive. I just wish the D2 had a dedicated headphone amplifier just like your STX able to drive the HD598 lood and without the low-end overpowering/mufling, considering you can select/switch the headphone impendance in the STX or so i've understood from what i ve read. Thus i would'nt have to jack a second amp(E7) in the front lineout jack of the soundcard like i do now, allthough i am not sure i am missing, theoretically, anything in quality by doing so, apart from the obvious gain in clarity and definition on the low-end because of the correct impendance of the E7. Perhaps i'll save up and get an STX or whatever comes up at the time and suits my head-fi needs. Thanks for sharing your thoughts though.

The D2 does have a headphone amp. Everything with a headphone jack has a headphone amp, they just aren't all equally powerful. The Essence STX has high output impedance as well, same as the E9 and maybe D2. The STX's gain settings have nothing to do with impedance, they're just labeled with recommended impedances that mean nothing. Every gain setting has the same output impedance.

 

[skydogis]

Thanks for the intel. So its a fact that the sound quality problem i ve run into is a matter of any Xonar with the HD598 because of their relatively low impendance (50 Ω). The Differences in the low-end are quite pronounced as i ve written and so i hope someone keeps that in mind if he's planing on spending money on that hifi pair. Thanks again for the info and the time. Read you around.

 

[Head Injury]

It's not a fact that all Xonars have problems. I'm not sure what the D2 output impedance is, I'm just assuming it's fairly high. Your experience seems to match my expectations, because I doubt the card is intentionally colored to be extra bassy.
 
I wouldn't generalize about anything, besides "high output impedance sounds different with HD598".

 

[mikeaj]

 
The thing to keep in mind is that they say 50 ohms, but it's clearly not 50 ohms around 100 Hz.
 
 
V_L = V_s * Z_L / (Z_L + Z_s)
 
Suppose we have 1V input, Z_L = 50 ohms at 1000 Hz but 275 ohms at 100 Hz, Z_s = 10 ohms (all frequencies), so V_L is the voltage the headphones see.
 
At 1000 Hz:
V_L = 1 * 50 / (50+10) = 0.833 V
 
At 100 Hz:
V_L = 1 * 275 / (275+10) = 0.965 V
 
 
This is a difference of 20*log10(0.965/0.833) = 1.27 dB boost at 100 Hz compared to other frequencies, maybe noticeable but not a huge deal...if the output impedance is 10 ohms.  The difference would be much larger for greater than 10 ohms.  This is just the FR change; there will be other effects too, but they may or may not be significant to you.