Originally Posted by arnyk
I would never attempt such a thing if I had full control. I would hook up an AVR via my PC's HDMI outputs.
If you already have a nice receiver, that's fine, but I don't, and I don't really see a point in getting one with my configuration.
For what you want to do, with many of these pro cards you have the option of using multiple cards - the M-Audio Delta series supports 4 cards for a total of 8 channels in and out using AP 24192 cards. There are also 4-in/out and 8-in/out audio interfaces (below).
Interesting. That, unfortunately, drives the cost up quite a bit, and I may not have enough physical slots in my PC to do this.
The big question about balanced I/O is whether you are having hum or other noise pickup problems? Most such problems come from the configuration, not the line length. The idea that balanced I/O is required or even advantageous when lines are longer than a few feet is an audiophile myth. In the PC world the typical commodity audio output is actually a very low impedance source and will drive the #!$$ out of long RCA lines.
Everything was fine when I had short cables to test it out. When I run 50ft RCA cables to the next room, I get a buzz in the speakers. This buzz is louder when lights are on. I was even picking up noises when scrolling around on web pages on my laptop near the speakers. I'm pretty sure interference is not a myth.
The subwoofers, interestingly enough, take RCA connections directly and appear to have some kind of noise canceling electronics -- the buzz is apparent when they're powered on, but only lasts a second or two.
Plan B is to put something you probably need - like a crossover (for bass management) or equalizer (for system tuning) close to the PC, and use its balanced outputs for the purpose you seem to want to address. Run unbalanced lines from a 8-output card like the Delta 1010LT to the equalizer or crossover.
How much would a decent EQ or crossover run that can handle 5+ channels and convert unbalanced to balanced? What would be the advantage over using a DI box?
Use cables like the ones in http://www.rane.com/note110.html
picture 17 or 18 and you will get a strong benefit from your balanced inputs even though you have balanced outputs.
Interesting -- goes back to my question of switching to XLR cables earlier. Maybe that can result in an improvement. It's certainly the cheapest option.
There is also a Delta 1010 (no LT) that has 8 balanced inputs and outputs. If there is no new stock of them at dealers, try eBay.
Looks like that would work, but I'm wondering how good the support is considering how old it is. It also sounds like there's a common issue with getting static due to capacitors going bad. I'll do some more research on it.
I have a lot of experience with DI boxes, but avoid them when possible for critical applications because they usually have transformers and somewhat nonflat frequency response. Behringer has a 4 channel DI box that has worked well for me in large venue AV applications.
Looks like their 8-channel version (ULTRA-DI PRO DI800) is not much more expensive. That might be a good choice. I'm really not sure on these. The Jensen transformers tend to be the most frequently recommended, but those would run at least $50 per channel.
The Rane Note I cited shows how to use specially made cables that are very cheap and easy to make to do many things that you might think you need a separate expensive box for. The balanced input you already have is a powerful tool. Most of the benefits of balanced I/O relate to balanced inputs. For years people have been building pro equipment that has a single balanced line per channel hooked to a connector like an XLR or TRS that we associate with balanced outputs and when put into a system driving a balanced input, the performance losses compared to true balanced outputs are microscopic. Inaudible by a big margin.
I'll order some cables and give this a shot first. That may be all I need. Thanks again for your detailed replies!