The KVM is irrelevant to this choice, it's just passing the sound to the speakers without processing it. So what you already know is correct, line level signal should reach powered speakers.

Did you try directly connecting that particular SB16 to the same speakers and using the same cables without passing through the KVM?

Yoghoo wrote on 2022-03-29, 18:37:

I normally use the Line Out jack of my soundcards to connect to my KVM switch which in turn is connected to a powered 2.0 speakerset. This normally works ok.

But a couple of days ago I did the same with a SB16 card (CT2940) and even on max volume (of both the card and speakers) the output was very soft. After switching it to Speaker Out instead of Line Out it worked correctly.

If I read the documentation it says to use Line Out for powered speakers (which I have). So I am a bit confused. Should you normally use Line Out or Speaker Out with a configuration like this?

It's not an exact science.

I'll assume you checked the internal settings for "voice/digital sound" "midi" "FM", etc. of that card. DOS tool or Windows panel.

Line level is defined rather clearly:
https://en.wikipedia.org/wiki/Line_level
yet, any sound card is free to adhere to those standards or less so.

The amplified output was meant for very weak passive speakers or, more likely, headphones.
I used the detachable speakers of a "ghetto blaster" passive on an SB32, that worked just fine.

As a general rule, don't turn down the original signal and then amplify it up again at the end. Because, e.g. if you reduce the game volume or the internal mixer settings, the noise floor will stay the same and so will all distortions picked up on the way to the speakers. But, internal sound card amps tend to be pretty bad, hence the habit of not using them.

But if necessary - it's not illegal to use a headphone level as input for powered speakers.
Every time someone hooks up an mp3 player or smartphone to powered speakers or a hifi amp (by the 3.5 mm jack and cable), they do so.
If it's too high, you'll notice some distortion in the louder parts.

Conventional KVM switch should be passive and just add some minor additional resistance to the process.
Some modern ones might be "virtual" as in "electronically distribute all the signals to different exits via one chip", more like an ethernet switch. But I don't think so.

konc wrote on 2022-03-30, 07:54:

The KVM is irrelevant to this choice, it's just passing the sound to the speakers without processing it. So what you already know is correct, line level signal should reach powered speakers.

Did you try directly connecting that particular SB16 to the same speakers and using the same cables without passing through the KVM?

Just tried it out and without the KVM (Aten CS64A) and the Line Out then works as expected. So the KVM does something with the signal. But like I said I don't had this problem with other PC's on the same KVM. The other PC's on this KVM have an Orpheus Sound Card, Avance Logic ALS100+ and Sound Blaster AWE64 (CT4520) sound cards.

Cuttoon wrote on 2022-03-30, 08:41:

I'll assume you checked the internal settings for "voice/digital sound" "midi" "FM", etc. of that card. DOS tool or Windows panel.

I indeed checked it. Tried it both in Windows 95 OSR2.5 and clean DOS on the same PC and got the exact same problem in both environments.

Yoghoo wrote on 2022-03-30, 08:46:

Just tried it out and without the KVM

Without the KVM, but using the KVM cable (only the jacks for the sound of course) I hope.

Yoghoo wrote on 2022-03-30, 08:46:

So the KVM does something with the signal. But like I said I don't had this problem with other PC's on the same KVM. The other PC's on this KVM have an Orpheus Sound Card, Avance Logic ALS100+ and Sound Blaster AWE64 (CT4520) sound cards.

It looks to me that the signal from this particular card is marginal and the added resistance from the KVM (small but existent) renders it inadequate.
If you're happy with the amplified signal use it, at most you'll have some clipping but I'm sure you're not after an audiophile setup with a SB 😉
In general what you know is correct, line level signal for powered speakers.

konc wrote on 2022-03-30, 09:34:

Without the KVM, but using the KVM cable (only the jacks for the sound of course) I hope.

Indeed.

konc wrote on 2022-03-30, 09:34:

It looks to me that the signal from this particular card is marginal and the added resistance from the KVM (small but existent) renders it inadequate.
If you're happy with the amplified signal use it, at most you'll have some clipping but I'm sure you're not after an audiophile setup with a SB 😉
In general what you know is correct, line lever signal for powered speakers.

It's indeed not for a audiophile setup. 😀 So will keep it on Speaker Out as it sounds very decent. Was just confused why it was necessary.