[jaddie]

Quote:

This document is difficult to understand for me because I'm a total stranger to the theory of signals and electric currents. What it seems to say is that plugging a balanced cable to two "balanced" ends doesn't guarantee that the signal will be noise-free. This document was first written in 1985 though, maybe things have changed a bit since then.

Physics hasn't changed in quite a few years.  The document is fine today too.  
Quote:

Versatility would be one of the most important criteria for me, and not being able to use any other application than iTunes is an eliminatory drawback of Apple's solutions.

Playing and controlling playback from a mobile device sounds fancy indeed, but it is not an exclusivity to Apple's AirPlay; foobar2000 has components providing remote-control and UPnP features, and there are apps for Android that can take advantage of these features.

A/V receivers are not a solution I want to consider at the moment: first they are more expensive, which means that at a given price, an A/V receiver will have either worse sound or less features - or both - than a stereo amp. Second, sending an undecoded signal to the A/V receiver will necessarily cause some problems when the audio track won't be encoded in a format that the A/V receiver recognizes. I fear it will involve perpetual tweaking, like having to convert everything to PCM on the fly from the laptop, and I'll be increasing the already endless list of threads titled "My digital output doesn't produce any sound"...

Sounds like you have your mind pretty well made up, so there's no point in my explaining the advantages in value and technology of an AVR, except to say that except for the really low end, today's AVRs have no decoding issues, no need for tweaking, and no need for PCM only.  There are lots of serious technical advantages, but if you're locked into a two channel amp, I won't take the time to explain them. 
 
The same is true on the iTunes/foobar issue. 
 
So, we're back to what to do about balanced wires.  All I can do now is reiterate.  Just using balanced cables doesn't get you a balanced interconnect, and has no better noise immunity than unbalanced cable.  To implement a high noise immunity balanced interconnect you have to have a balanced source and a balanced destination.  The destination must have high common-mode rejection (don't bother searching for specs, they are hardly ever there, but that's the critical figure of merit).  If you can't find a balanced output DAC, you'll have to use an external device to create a balanced output.  Your amp has to have a balanced input, or a device in front of it that has one and converts to unbalanced.  The cost of these devices ranges from $50 at each end on up to $1000 at each end.  
 
There are a lot of balanced output DACs, but you'll have to either look at the high end of consumer audio or look at professional devices.  For amps, the ones with balanced inputs are clustered in the high-end market, so you'll pretty much need a conversion device or pay up.
 
Let me offer one final reality check, which you can pick and choose from if you wish.  The devices that make the biggest changes in sound quality are, in descending order of impact:
 
Speakers (huge, quality is everything here)
Number of speakers and channels (huge, everyone can hear the difference every time you double the channel count)
Speaker placement (significant. Bad placement will undermine everything else on the list.)
Room treatment (can be very significant, depends on the room.  A bit of treatment in the right place is a very audible improvement.)
Calibration systems (Audyssey, Pioneer MCACC, Yamaha YPAO, etc.) (particularly significant if you can't optimize the above two. And any cal system beats none, even with treatment.)
Audio file formats, bit rates, etc. (this one could be bumped up the list, but it's assumed you're already at FLAC, but once you're at high enough quality it doesn't matter anymore)
Play software, amplifiers and AVRs, DACS (negligible, imperceptible)
Exotic wire types and power conditioning (no difference at all except in very extreme circumstances)
 
Might have missed something, but it's probably not significant.

 

[esldude]

If I may make a suggestion.  You would do well to take a USB signal from your laptop to the rest of your system.  Solves all your noise concerns with the long cables to the amp.  Normally USB 2.0 is limited to 5 meters.  You can get monoprice active extenders, and they work I have used one for 192khz/24 sound.  Here is one for 20 meters.
http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10303&cs_id=1030312&p_id=7533&seq=1&format=2
 
They can be had in longer lengths.

So you either will feed a DAC with USB input or use an USB/SPDIF converter.  That can be located at your amp.  You need have no worries about various formats.  Any audio from any source on the computer can be sent out over the USB to the rest of your system. 
 
Now a good suggestion you seem resistant to is getting an AVR.  I don't know your budget and such, but a very good option is getting a Denon AVR off your local craigslist.  These are well made, with good digital and analog performance.  They can be had for a tiny fraction of their original cost.  Any of the better Denon AVR's from the last decade will do up to 192khz/24.  They have several digital inputs and analog as well.  You need not have a separate tuner as a good one is built in.  They would take a digital input from a USB/SPDIF converter and work just fine.  No encoding recognition issues will ensue.
 
If you still don't like that, an integrated amp combined with a DAC should work for you.  Either a DAC with USB input or any one of a number of inexpensive converters feeding the regular digital input of a DAC.  The Musical Fidelity V-link is a good USB/SPDIF gizmo for not lots of money, but there are many others to choose from.  Either way going over USB from the laptop covers any concerns about balanced cable or not. 
 
As for the Rane article about balanced cable being from 1985, the physics of electrical audio signals over balanced wire haven't changed since 1985 so all of that info is exactly the same. 

 

[jaddie]

Quote:

If I may make a suggestion.  You would do well to take a USB signal from your laptop to the rest of your system.  Solves all your noise concerns with the long cables to the amp.  Normally USB 2.0 is limited to 5 meters.  You can get monoprice active extenders, and they work I have used one for 192khz/24 sound.  Here is one for 20 meters.
http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10303&cs_id=1030312&p_id=7533&seq=1&format=2
 
They can be had in longer lengths.

So you either will feed a DAC with USB input or use an USB/SPDIF converter.  That can be located at your amp.  You need have no worries about various formats.  Any audio from any source on the computer can be sent out over the USB to the rest of your system. 
 
Now a good suggestion you seem resistant to is getting an AVR.  I don't know your budget and such, but a very good option is getting a Denon AVR off your local craigslist.  These are well made, with good digital and analog performance.  They can be had for a tiny fraction of their original cost.  Any of the better Denon AVR's from the last decade will do up to 192khz/24.  They have several digital inputs and analog as well.  You need not have a separate tuner as a good one is built in.  They would take a digital input from a USB/SPDIF converter and work just fine.  No encoding recognition issues will ensue.
 
If you still don't like that, an integrated amp combined with a DAC should work for you.  Either a DAC with USB input or any one of a number of inexpensive converters feeding the regular digital input of a DAC.  The Musical Fidelity V-link is a good USB/SPDIF gizmo for not lots of money, but there are many others to choose from.  Either way going over USB from the laptop covers any concerns about balanced cable or not. 
 
As for the Rane article about balanced cable being from 1985, the physics of electrical audio signals over balanced wire haven't changed since 1985 so all of that info is exactly the same. 

He want's to plug his headphones in to his DAC.  Extending USB and locating the DAC across the room eliminates that.  If there's a ground loop between the DAC and the amp, USB extension will not fix it, even if the DAC is located at the amp.  Optical would, if you can live with that.  I think there are 10 meter optical cables. Of course, he still can't plug his headphones into the DAC and operate foobar from the computer.
 
Good points on the AVR, but I get the feeling it's already out of the question.  I look at integrated amps as the last bastion of the 1970s. Can't imagine buying one today.  I'd look at a preamp/power amp combo first, but the average AVR does so much better...oh well. 

 

[esldude]

Quote:

He want's to plug his headphones in to his DAC.  Extending USB and locating the DAC across the room eliminates that.  If there's a ground loop between the DAC and the amp, USB extension will not fix it, even if the DAC is located at the amp.  Optical would, if you can live with that.  I think there are 10 meter optical cables. Of course, he still can't plug his headphones into the DAC and operate foobar from the computer.
 
Good points on the AVR, but I get the feeling it's already out of the question.  I look at integrated amps as the last bastion of the 1970s. Can't imagine buying one today.  I'd look at a preamp/power amp combo first, but the average AVR does so much better...oh well. 

Sorry, missed that he wanted to plug headphones into the DAC at the location of the computer.  I knew the USB wouldn't solve any ground loops.  But it took care of interfacing XLR connectors on both ends which aren't likely on equipment if he is keeping to low cost options. 
 
I wouldn't go with an integrated either, but they can sometimes provide acceptable functionality cheaper than separates. 
 
On the other hand, maybe his better option is still to put his DAC at his main system, and run a long extension to his headphones.  Don't see that it would much matter as he will have some cabling running the 10 meters anyway.