In addition to its work in the networking space, Realtek has a significant share of the integrated audio market, too. The company sells a variety of codecs with different feature sets. The Rampage III Formula motherboard I'm using comes equipped with an ALC889, so that's the multi-channel codec I'm testing alongside the discrete solutions.
Except for the very similar ALC898 and technically better ALC1150, neither of which is listed in the table below, Realtek's ALC889 is pretty much top-of-the-line. Beyond sporting the most advanced specifications, it's also Realtek's only codec with support for DSD (though we couldn't find a suitable ASIO driver to get it working with foobar2000).
You can purchase the ALC889 in volume as an OEM for an indicative price of ~$2 per chip (or less, depending on the volume ordered), which means that the cost it adds to your motherboard is probably less than $10. Talk about an indicator of how commoditized the integrated audio market is.
Before you lean on integrated audio, be sure to do a little research into the codec your motherboard includes. Specifically, higher-sounding part numbers aren't always indicative of a better component. For example, the popular ALC892's specifications are inferior to the ALC889.
According to its datasheet, the ALC889 sports headphone amplifiers integrated at six output ports. They drive the Sennheiser HD 800s at 93.6 dB(A), and as such have more than enough power for anything at or below 300 Ω.
As you'll see, the ALC889 appears to be the least hi-fi of the devices we're testing, with a 1.4 dB(A) difference at 100 Hz. It is quite easily distinguishable in a pure-tone comparison at that frequency, although it is much harder to detect in regular music-listening scenarios (as at 1 kHz and 10 kHz the volume difference is much smaller).
We also want to explore this codec's output impedance. At 77 Ω for the recommended implementation, it is by far the highest (almost by an order of magnitude over the second-highest) in our round-up. Is that a factor in the real world?