Simple Component Upgrade STAX SRM-252S Headphones Amplifier - Part 1

STAX SRM-252S amp and the headphones SR-L300 is an entry level in STAX line up. They have more beefy line up above that with the price tag very surprisingly expensive. And this STAX SRM-252S is actually a very good amp, but can this improve? We know that mostly in entry level product, the manufacture usually cut some corner in the components. If they are improve, how is the result?

As usual, open up this unit is quite simple. I just using screw sets that contain many size of hex and Phillips screw.

After the front bolts are remove along with the volume control knob, now continue to remove the bottom screw.

There is four bolt and three of them are behind the feet. It only attach by double side tape and can be reuse again.

Once all screw has been remove, open this unit is only by pulling out the board.

First things to attempt in this upgrade is changing the input RCA. They are good connector but look cheap.

I remove them immediately.

I always using CMC connector, they are very reliable, good looking, nice material and also affordable.

It is just plug and play.

Since this new RCA socket is an OEM product, I need add some cables for jumper. This cable is a very high quality silver coated cable with Teflon jacket.

RCA plugs replacement is now done. It is look way better.

Going forward, I see little caps near the DC input socket.

It label C31 is only 1uF and C36 near the transformer is 33uF electrolytic capacitor.

I replace them with 47uF Elna Silmic.

I change them both.

How tiny the OEM capacitors they use here. Why also they are using different class of capacitor?

This is the first upgrade I did in this STAX amp.

For sure, it is look sexy now.

And how about the sound improvement after the upgrade?
I don't know why the sound become boxy and dull after this upgrade? I try to listen at the same system before and it is clearly doesn't make any improvement. Yet, I it is decline in sound quality. Is it because the new RCA socket? Maybe the silver cables doesn't suit this amp? Or the capacitors not yet breaking in? Don't follow this upgrade yet, this is still not right:(

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