I have old "JBL Pro" unpowered speakers that came with a now dead
Compaq Presario system.
I replaced that system with a new one wich have VIA AC'97 on board
audio. When the speakers are plugged to the 2speaker out" of this
board, I can barely hear the sound.
I heard that "onboard" audio doesn't have an amplifier and that I had
to either find a compatible audio card or buy amplified speakers.
Yes that's correct, OR buy an amplifier to plug in between
the sound card and speakers. I doubt that those particular
speakers are worth the investment of an amplifier so the
former two options might be better.
What specs do the audio card has to meet to correctly use these
speakers ? Any suggestion ?
It will have an onboard amplifier chip, but unfortunately
too few mention this detail clearly. The indirect
assocation is often that there are a pair of jumpers onboard
the card to choose between speakers and line-out.
In recent years few if any cards had such an amplifier, and
whether an older card is acceptible for your uses may depend
on your needs. Basic 2 channel sound as expected from 2
speakers would work fine but more than 3 channels would not.
Further, the sound card would have to have a driver that
supports your operating system.
Here is the newest card I know of that has the onboard amp
chip (thick rectangular chip towards the bottom left in the
picture), and it does happen to have more than 2 channels
which I had forgotten,
http://www.txmicro.com/details.htm?productid=1F-3589
On their homepage search for "Creative Labs Sound Blaster
4-Channel PCI Soundcard"
http://www.txmicro.com
You'd have to download drivers from Creative's website.
It's a better sounding card than today's $8.50 cards, but I
doubt it supports some advanced features like positional 3D
audio in games. With only 2 speakers it wouldn't matter.
What is the best move : buy another audio card or amplified speakers ?
Given I'm on a low budget, I can't afford both !
Depends on how low the budget.
For $8, you won't get speakers that are very good but I'm
not sure "exactly" how bad the current speakers are. For
under $20 delivered, the above sound card is probably the
best option, unless you go looking around for deals on
speakers... which is not a bad idea, given enough searching
you should be able to find some for $20. Try to avoid the
very small or thin ones, especially off-brands if you get
2.0 channel speakers. I don't know which inexpensive
speakers are best but here's an example,
http://www.newegg.com/Product/Product.asp?Item=N82E16836117121