maxxy
Head-Fier
- Joined
- Jan 13, 2004
- Posts
- 80
- Likes
- 10
Question is pretty self explainitory. Would like some insight as I have no clue why one would be better than the other.
Cheers
Cheers
Originally Posted by maxxy Question is pretty self explainitory. Would like some insight as I have no clue why one would be better than the other. Cheers |
Originally Posted by Jon L People have struggled long and hard to improve the evil that is spdif and run-of-the-mill USB music connection. PCI connection is a great-sounding digital connection method for music that avoids the dreaded spdif connection, and even the cheapest soundcards enjoy this advantage. |
Originally Posted by Jon L USB DAC Disadvantages Despite the promise of bit-perfect, low-jitter USB music connection, the vast majority of USB devices/DAC's fail miserably. The holy grail of USB connection will have to have all of the following: 1. Asynchronous USB protocol--the best, lowest-jitter method, but I'm not aware of ONE USB DAC on the market today that uses asynchronous protocol, not one. Most consumer devices use the worst synchronous method, which are in fact worse than the usual spdif method. The better ones use "Adaptive" mode, which can sound better than spdif, but it's still not as good as USB can be. 2. Direct USB-I2S-DAC connection. Most USB DAC's USB chips convert the signal back to the dreaded spdif, which is then sent to the usual CS spdif input receiver chips, completely negating the benefit of USB (supposedly spdif-free) connection. Fortunately, more and more small companies are starting to use I2S connection using the PCM2706/7 USB chips, such as the new Scott Nixon USB DAC, DDDac, Empirical Audio, but these are far and few between. USB DAC Advantages USB digital connection 'can' sound better than spdif, provided the caveats listed above. Despite my disappointment with current state of USB connection today, I have high hopes for future USB DAC's, especially if TI decides to market new USB chips designed for audio, with native asynchrouns protocol support. That'll make my day (year, decade)! Also, as mentioned above, unlike soundcards, USB DAC's have no limits as to how elaborate the designer can go as far as internal parts quality, power supply quality, etc. Sky is the limit. The Future PC audio will have come of age if all of the above criteria are met, and if even the cheapest, standard PC ships with native asynchronous USB support, enabling the use of high-quality direct USB-I2S DAC's. I personally look forward to this future, and there are little signs here and there that hints the future may not be that far off. In the meanwhile, for the present, I believe the best compromise is to use a high-quality soundcard's digital output (possibly modded) into an outboard DAC with good jitter-rejection circuitry. Another way is to buy a USB DAC that at least uses adaptive mode USB protocol and direct I2S connection. |
Starting with Windows 98, Usbaudio.sys supported the adaptive and synchronous endpoints, but it did not implement the asynchronous endpoint correctly. Full support for asynchronous endpoints in Usbaudio.sys is planned for Windows Longhorn. |