Nice! Line-level outputs on an SB Pro 2. I wish I could replicate that on a CT1600.

Does your problem follow the volume of the hardware mixer?
If so, the master AND the wave volume?

Any chance you could take better pictures of the board? The posted ones are too blurry to make out the traces.

Thanks!

The RCA conector seems not to be regular output because of there's no signal on them (3.5 jack works properly). I don't know what they for. That's one of reasons to get the manual.
I uploaded better quality pics.

The board seems to be ok except little bit melted (WTF???) J1 connector in the left upper corner. Also several of its pins have signs of tin.
And one more thing to mention. When I've got the card (it made a long way from Canada to Russia) I noted of two "slided" SMD components - C43 cap and R24 resistor. I've thought it was happend during shipment but later I found them already broken on the published item's photo.

The seller sold the card with 60 day warranty so I was not so attentive to the details buying the card. But it seems I had to. And I give you advice to look what are you about to buy sharply prior to payment.
I resoldered broken components to their corresponding locations prior installing the card into PC slot because I don't know if any further damage it can bring to itself or motherboard in its current shape. Anyway those components seems to be related to LMSI and that sound trouble that I began this topic with is coming from other place on PCB.
The card itself is beautiful and rare. I'd wish to fix and keep it rather to return to seller although I've got it expensive enough to have-no-headaches.

Does your problem follow the volume of the hardware mixer?
If so, the master AND the wave volume?

I'm also curious as to the purpose of those yellow jumper wires on the interface, which oddly enough seem to also route to the audio output if you follow the traces.

Thanks for advise!
I found that distortion amount in right channel really depends on hardware mixer volume. It seems that Diagnose.exe when started reinits the card and therefore ignores mixer settings (sbpset.exe).
When set to 250 both master and voice, the sound in right channel is very distorted especially on low freq sounds (drums etc). But the left channel works OK.
When set to 140, the right channel still a bit distorted, but in silence (between parts in MODs) there's background noises. When I stop playing, all these noises are gone.
When set to 10, sound is almost normal, but the background noises come to front so this mode is unusable.
The issue comes in stereo mode only (at least in monofonic I don't hear it).

I replaced this defective card with a regular CT1600 and checked it at the same conditions. I've got NO distortion/noises neither in Diagnose.exe neither in Impulse Tracker (that's the easiest way for me to play a stereo .MOD file) at any mixer and any volume knob settings.
Does someone know how the audio is routed on this (CT1620) card? It seems like defective amplifier or (what's worst) defective Creative's mixer chip.
BTW, I connected the amplifier to RCA connectors and at maximum volume level (250/250) I've got audio output. But it's still way too off to be used instead of 3.5mm jack.

I've cut those yellow wires on the back side of the card by sidecutters (the PCB stays intact).
The audio otput became way too off even on 3.5 jack. At maximum volume levels the left channel brings background noises only while in the right (defective!) there's a sound but far-far away.
I think I'd better resolder those wires back to their appropriate places.

It seems so I am the only CT1620 card owner here on VOGONS? 😀

You might want to check continuity on the yellow wires.
One of them looks like it could be damaged.

Yes, there's a little damage to the isolation but the wire itself is ok
Thanks

Resolderd those yellow wires back to corresponding points. Sound volume returned to the previous level. Distortion in the right channel still audible as where we were started at.
Does anybody has the manual and/or driver set for this card model (CT1620)? Need them hardly. Am I alone owner.
If someone has such card, please post the picture of it's back side. I need to know whether those yellow wires are factory made or not.