[Ivan TT]

I also believe that opamp’s ability to drive a capacitive load (and cable+earphones have at least SOME capacitance) is a factor. This issue is often solved by resistors in series with the output, removing them completely may cause opamps to oscillate, this will apply to AK4497 based DSD’s balanced output.
However since AK4497 DSD SE output uses a discrete output stage its ability to handle capacitive loads is unknown, as well as if its ability of handling short-circuit condition (which happens for few seconds when you turn Zishan on by the way), so SOME resistance should be maintained.

 

[calico88]

I use burson V5i, does this opamp has internal short circuit protection?
no idea how to check, can not find that circuit protection on burson website.

 

[kookaudio]

Made some mods to my zishan. Thanks to IvanTT for the good suggestions!

LM4562 replaced with LT1364
OP275 replaced with AD8620
LDO's replaced, same for caps around the dip8 socket.
22ohm resistors at the output replaced with 10Ohm.

Soundstage is wider, separation of instruments if more noticeable. Of course those are details, it is not night and day but noticeable for sure.
At the moment I think that I won't get any benefit from other upgrades until I'll buy a more resolving pair of iem (currently 1more quad driver).

BTW this little mod is really cheap but the improvement is clearly audible. Recommended!

Weren’t AD8066 preferred in place of the OP275?

 

[Ivan TT]

Weren’t AD8066 preferred in place of the OP275?

In my experience they have slightly different presentation that may or may not have good synergy with your earphones/sonic preferences and taste.
AD8620 comes straight from the datasheet and has nice rounded sound, noteadbly quality midrange.
AD8066 is more detailed in comparison and produces one of best sounstages (shimmering and deep) I have ever experienced, but its midrange is nothing special, as in “neutral”. Don’t remember if there was any difference in lows, sorry.
All above is IMHO and I would like to hear other opinions on these opamps too.

 

[Themilkman46290]

I tried the 8066, felt it was a bit dull and preferred the 8620, but alot of people like it. Although i had a hard time choosing between 8620 and 823 (warm and bassy, good imaging but not as detailed and clean as 8620)

 

[Ivan TT]

In the meantime a bit of AB testing against class-leading fairy lights equipped DAC-amp (DSD acts as SPDIF coaxial transport). I will NOT post impressions, as I don’t feel like blowing my own trumpet at all. Black box lurking in background is Z2 (obviously it has 1622 and removed output caps)

@ThanosD recognise the cable?

 

[ThanosD]

@Ivan TT Haha, I surely do. Great cables. I already have one balanced that I use with the T2s, and one single ended, on my Custom IEMs.

Btw, I changed the capacitors, I will post my impressions later today probably

 

[Themilkman46290]

So now that i have nearly finished the ak4497 dsd, i want to try and improve my ak4490 dsd, but it seems there is not many tutorials or much of any info, maybe you guys have a suggestion?
I thought maybe someone can suggest something, was wanting something a bit darker, was thinking of muses8920, but not sure if it will fit, i was also thinking of possibly installing some leads and a dip8 socket but scared to ruin the solderpads

 

[Ivan TT]

I have (yet another) crazy idea...
There’s a bit of output caps discussion here and lack of space is a limiting factor, so higher capacitance one’s would not fit, but capacitors could be paralleled which gives twice the capacitance (and twice the price) and half ESR, and shift HPF cutoff frequency down by 1 octave, which could be beneficial for low impedance earphones bass response.
I removed all decoupling audio caps in my DSD and there’s no coming back for me, but I don’t see too much trouble fitting x2 6.3mm capacitors in DSD. Anyone keen to give it a go?

 

[kookaudio]

In the meantime a bit of AB testing against class-leading fairy lights equipped DAC-amp (DSD acts as SPDIF coaxial transport). I will NOT post impressions, as I don’t feel like blowing my own trumpet at all. Black box lurking in background is Z2 (obviously it has 1622 and removed output caps)

@ThanosD recognise the cable?

Mine is definitely the cheapest switch (maybe 3usd)

 

[Merlin-PT]

So now that i have nearly finished the ak4497 dsd, i want to try and improve my ak4490 dsd, but it seems there is not many tutorials or much of any info, maybe you guys have a suggestion?
[...]
I thought maybe someone can suggest something, was wanting something a bit darker, was thinking of muses8920, but not sure if it will fit, i was also thinking of possibly installing some leads and a dip8 socket but scared to ruin the solderpads

I would start by what you saying, replace the possible fake (I don't know what's in that model) opamps and audio capacitors.

Putting a permanent socket in the soic opamp looks desirable if it fits inside the case, but I never tried it yet.
At some point I used a temporary dip8 socket with some wires soldered to the soic8 pads in Z2 PCB and it allowed to try all opamps there.
The only problem I saw, was the wire must be very flexible not to stress the pads when moving the dip8 socket on the other end.
I used a thin and flexible wire and a lot of care. This was temporary, only to select the opamp, other options wouln't fit the bottom of the Z2 case.

If you possible, next time you open it take a photo so we can also see the 4490 insides.

 

[Themilkman46290]

I would start by what you saying, replace the possible fake (I don't know what's in that model) opamps and audio capacitors.

Putting a permanent socket in the soic opamp looks desirable if it fits inside the case, but I never tried it yet.
At some point I used a temporary dip8 socket with some wires soldered to the soic8 pads in Z2 PCB and it allowed to try all opamps there.
The only problem I saw, was the wire must be very flexible not to stress the pads when moving the dip8 socket on the other end.
I used a thin and flexible wire and a lot of care. This was temporary, only to select the opamp, other options wouln't fit the bottom of the Z2 case.

If you possible, next time you open it take a photo so we can also see the 4490 insides.

Here you go

Maybe that can help

 

[Merlin-PT]

What you are saying looks like a good plan.

I would solder some temporary wires to a dip8 socket, to select the op275 replacement.
I would solder all wires flat to the PCB and pointing the bottom of the photo, so the dip8 socket can leave the right side between the two boards.
If you have the space, maybe a low profile adapter could fit inside, instead of the wires. Depends if it fits, if you have one and if you want to change the opamp after the final selection.

I would also change the wima and elna caps.

If money is not an issue, you could replace the buf634 for the same model (just in case) or save it for last and only replace it if you are not satisfied with the sound. I never tried buffers yet to recommend anything.

Maybe others have more suggestions.

 

[Draknodd]

would you tell me the difference using 10ohms ?

Hybrid iem will sound more neutral in mids and highs. Probably it allows to use some fullBA iem but I have not a pair to test this

 

[kookaudio]

Did anybody test this...?