Following up since we exchanged posts . . .
I am wondering whether the SoundBlaster is too old. That is why I was inquiring whether your video card had a sound chip. Your Nvidia 9800 GT is a good card and I believe it also includes a sound chip. If it does, the audio signal (and video signal) from the Nvidia 9800 GT is transferred to your monitor with an HDMI cable.
Another thing I wonder about is whether your SB 5.1 was intended for 32-bit operating systems? Trident is a 64-bit system, but does run some 32-bit hardware. Just wondering whether that is something to check out.
You stated that your motherboard contains a sound chip. It is enabled and disabled in the BIOS. If you are not using the built-in sound chip, you must disable it in the BIOS in order to cause no interference with an add-in sound card. If you are using the motherboard sound chip, you must remove the SB 5.1 and then enable the motherboard sound in the BIOS.
Another thing to check is to make sure you have the correct driver for your sound card. I reviewed the FreeBSD 12-RELEASE Hardware Notes (found @ https://www.freebsd.org/releases/12.0R/hardware.html#support). I could not find any notes on FreeBSD 13 (which is what Trident is based on). The Hardware notes state the following with respect to SoundBlaster cards (You will have to figure out which SoundBlaster name in the notes matches up with “SoundBlaster 5.1.”):
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The [snd_emu10k1(4)] driver supports the following sound cards (note the (4) refers to which part of the FreeBSD “man” pages (instructions for specific commands, how to setup devices, etc.) :
- Creative SoundBlaster Live! (EMU10K1 Chipset)
- Creative SoundBlaster Audigy (EMU10K2 Chipset)
- Creative SoundBlaster Audigy 2 (EMU10K2 Chipset)
- Creative SoundBlaster Audigy 2 (EMU10K3 Chipset)
The [snd_emu10kx(4)] supports the following sound cards:
- Creative Sound Blaster Live! (EMU10K1 Chipset). Both PCM and MIDI interfaces are available.
- Creative Sound Blaster Audigy (CA0100 and CA0101 Chipset). PCM and two MIDI interfaces available.
- Creative Sound Blaster Audigy 2 and Creative Sound Blaster Audigy 4 (CA0102 Chipset). PCM support is limited to 48kHz/16 bit stereo (192kHz/24 bit part of this chipset is not supported).
- Creative Sound Blaster Audigy 2 Value (CA0108 Chipset). PCM support is limited to 48kHz/16 bit stereo (192kHz/24 bit part of this chipset is not supported). There is no MIDI support for this card.
The [snd_emu10kx(4)] driver does not support the following sound cards (although they have names similar to some supported ones):
- Creative Sound Blaster Live! 24-Bit, identified by FreeBSD as
- Creative Sound Blaster Audigy LS / ES, identified by FreeBSD as
- All other Creative sound cards with -DAT chipsets.
- All Creative X-Fi series sound cards.
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You should also review the FreeBSD Handbook @ Section 7.2. that is titled “Setting Up the Sound Card” You can access the Handbook here: https://www.freebsd.org/doc/handbook/book.html
Then you can navigate through the Table of Contents to Section 7.2
Can your sound quality be adjusted by tweaking its settings to ensure that you have a high quality output? Newer computers, including Macs, use “high definition audio” which is capable of sampling resolutions from 8 to 32 bits and sampling rates of up to 192 kHz. I do not know if an SB-5.1 can meet those specs. I have read that Mac’s are set at 44khz, 16 bit stereo output.
In conclusion, troubleshooting is aided by reference to Discourse like you have done, but it is also aided by reference to the FreeBSD manuals – the FreeBSD Handbook and the FreeBSD Hardware Notes – both linked above. (Trident is based on FreeBSD) The Handbook often identifies the commands to perform troubleshooting, the configuration files on your system to edit, and the changes that are made to the commands in the files.