Audio out is better than USB; digital audio is best of all.
titaniumducky said:
USB is not really advisable for audio. It's exists as an option for those without any other option. Since you have a PowerMac, definitely use something that uses your line-out
If you have a G5, get something that uses the optical-out; you'll get amazing sound!
Porting Mac sound through a PowerMac audio line-out to an external receiver (just a mid-range Pioneer) then to any good shelf-top speaker (Bose, JBL, Boston, etc.) or a good package as described above, provides incredible sound.
Bose can give you amazingly BIG sound in little boxes for ease of placement around a computer.
Because I edit movies (non-pro) and want to check them before and after I burn them to DVD, I have gradually set up a small studio (hey, it just happened piece by piece). I'd never thought about it before, but one side is for computer NLE creation, then the other is for testing it out for TV and consumer use. I got the smallest (20" I think) Panasonic flat screen TV that had full
S-Video type inputs that I could find (it was "last years model" and cheap) so I could "see" what my stuff looks like on a (non-monitor) real TV.
I purposefully use a very inexpensive (open box [really - NO box, remote, manual, etc.]) Panasonic DVD player for the
basic consumer "test", pipe
sound through a Panasonic (hey, it just happened this way, folks; I like other brands too)
100w per channel 5.1 and some narly top end shelf speakers for surround, a Bose subwoofer, and a non descript center speaker I got on supersale at Fry's so dialogue on TV sounds more normal.
Everything was acquired piece by piece, at Ultimate Electronics, Fry's Elec., Best Buy, and wherever I stumbled upon an incredible "deal" (I even whine a little to get even more discount; I'm bad

) An old top-end Hi8 SONY takes care of 8mm archives, JVC takes care of VHS & SVHS, and all the sound goes through the Panasonic receiver.
This is NOT my entertainment / recreation system (that's Adcom, Marantz and JVC components).
Would I like to have a 5.1 or 7.1 set of matching speakers? sure - make me a deal! And, there are DEALS - look for plain
BROWN BOX sales of "refreshed" speaker sets (especially for computers) at Fry's Elec., Best Buy and sometimes Ultimate; often
half price or less, and they are essentially the same thing as the new ones in the fancy boxes with colorful labels 2 isles over ...except for the price (often, same warranty).
Yamaha has some awesome 7.1, 6.1 and 5.1 consumer receivers & amplifiers (but, I like Bose speakers better), often at close out prices (Ultimate),
or online for their
Cavit computer products.
http://www.yamahamultimedia.com/yec/idx_cavit.asp
Although USB or analog, the Cavit receivers manage audio signals outside of a computer, thus relieving the CPU and RAM of any burden.
The point I'm trying to make is that instead of being limited to "powered computer speakers" from Logitech, HK, or Klipsh, good sound can be easily and inexpensively acquired using other speaker and amplification alternatives than are typically supplied by dealers in computer accessories.
Especially for audio, cross-over between high-end consumer sound and sophisticated computer audio has finally arrived...and it all SOUNDS good.