Xonar STX Op-amp change

[Rullknufs]

I have read that it is possible to easily change the op-amps of the Asus Xonar STX to "better" ones.

I have a pair of AKG K271 MKII headphones, will i be able to hear any difference?
If i understood right, you just pull the old op-amp from the socket and replace it with the new one? No soldering or permanent modifications needed?

What op-amps could i change to? Where can i find them? Is it worth the cost?

[5th element]

Originally Posted by Rullknufs

I have read that it is possible to easily change the op-amps of the Asus Xonar STX to "better" ones.

Yes this is true. You can easily change the I/V converter opamps and the differential stage opamps.

Originally Posted by Rullknufs

I have a pair of AKG K271 MKII headphones, will i be able to hear any difference?

Probably not and this isn't because your headphone aren't good enough.

Originally Posted by Rullknufs

If i understood right, you just pull the old op-amp from the socket and replace it with the new one? No soldering or permanent modifications needed?

This is correct.

Originally Posted by Rullknufs

What op-amps could i change to? Where can i find them? Is it worth the cost?

Opamps can cost quite a lot of money, but as the STX uses duals this removes some of the ridiculously priced singles from the equation.

The differential configured opamp already uses a high quality opamp from national semiconductor that has been designed specifically for high quality audio.

The I/V opamps use a version of the NE5532. This is quite an old opamp, but it gets the job done fine, it has been used in a lot of musical fidelities high end digital gear to do the same job as an I/V converter.

The output of the I/V opamps either feed into the headphone amplifier chip or the differential stage opamps. So if you're going to want to change something specifically for the headphones then all you need to change are the I/V opamps. Asus details which ones these are on their website under the downloads for the card.

You have to watch out what opamps you choose to use or change because some of them will not be happy driving a capacitive load, which is what the opamps in the STX are doing. The board layout is decent enough such that most opamps wont become unstable, but some, once again, require specific attention paid to guarantee proper operation. Usually the ones that aren't happy driving capacitive loads are the ones that are finicky about their implementation.

One thing that I find a surprise with the ST/STX is that Asus don't offer a list of opamps that are suitable for swapping in and out. You can't just go throwing any old opamp at the thing and expect it to work properly, even if the pins are of the right configuration.

[Rullknufs]

Thanks for detailed explanation. If i wont hear any difference, i think i'll skip this project