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NVIDIA has made much of the audio capabilities in its nForce2 chipset, and NVIDIA's progress here hasn't gone unnoticed at VIA. VIA has begun making its own push into the discrete audio market with products its acquired in the purchase of ICEnsemble. Now, VIA's chipset audio is getting some attention, as well. For the KT400A, VIA has pulled together a combination of hardware and software solutions under the umbrella of the marketing name "Vinyl Audio" to compete head-to-head with nForce2 sound.
The first and most obvious piece of this puzzle is the six-channel AC97 audio controller integrated into the VT8235 south bridge chip. This controller isn't brand-spanking new—the VT8235 been around for the life of the KT400—but it is relatively new, and it's VIA's first six-channel effort. This controller doesn't have lots of DSP-style intelligence like the nForce2 APU, but it can produce six clean channels of audio output.
 The VT1616 codec is the KT400A's ticket to crisp audio output |
The VT1616 chip can convert six audio channels simultaneously with 20-bit resolution. VIA claims a signal-to-noise ratio of 97 dB in discrete sound cards, where the VT1616 is likely to be paired up with VIA's Envy24PT controller for low-cost, high-quality audio solutions. In the noisier environment of a motherboard, VIA claims the VT1616 can achieve a signal-to-noise ratio of 90 dB.
To aid with clean signals, VIA's architecture keeps the headphone amplifier separate from the codec, because amps generate heat and noise. VIA's marketing name for this architecture is "CoolAmp." The VT1616 also includes the ability to perform hardware downmixing, which removes the burden of combining discrete audio streams from the system's CPU. This tech also gets a marketing name, the vaguely spunky "DualMax." VIA claims boards using the VT1616 can produce higher quality audio than nForce2 boards with inferior codecs, which is a plausible claim, because codecs often limit audio output quality. VIA doesn't say so explicitly, but clearly nForce2 boards with the ALC650 are in its sights.
The final piece of the Vinyl Audio puzzle is a new software driver created using technology licensed from Sensaura. This licensing deal gets VIA access to the same suite of software audio technologies NVIDIA has licensed for the Xbox and nForce APU. The Sensaura drivers provide VT1616-based audio solutions a full range of positional audio features, including compatibility with all the major audio APIs: DirectSound3D, EAX 1.0/2.0, A3D 1.0, and I3DL2. Sensaura's software algorithms will, of course, require some CPU overhead, but VIA claims the impact on performance is fairly minimal.
With Sensaura drivers installed and a VT1616 codec, KT400A motherboards should offer a much more compelling mix of audio quality, performance, and compatibility—particularly for 3D gaming—than most current KT333 and KT400 boards. If VIA can persuade its motherboard partners away from using Realtek's popular (and no doubt dirt-cheap) ALC650, then KT400A boards may be much more competitive with nForce2 solutions, at least for analog output.
The VT8235/VT1616/Sensaura combination seems unlikely to match the nForce2 APU on every front. NVIDIA has licensed a real DSP core and integrated multiple copies of it into the nForce2 APU, which should cut CPU overhead. Also, the nForce2 APU can encode Dolby Digital output for use with a Dolby-capable amp/receiver. With digital outputs, a low-quality DAC on the motherboard will be bypassed entirely.
VIA provided us with a beta copy of its Sensaura drivers for testing with the KT400A, but unfortunately, we weren't able to test it adequately. Our first KT400A reference board, an early revision, wasn't stable in 3D games. The second board was rock solid in gaming, but it wouldn't POST with on-board audio enabled. We'll have to test with a real, shipping product at a later date.
