Paul Mah of Dagogo has written an extensive review of the BMC PureDAC, and is weighing in on the PureUSB1 as well. I direct interested parties to his review for comprehensive coverage of their function as I do not wish to be redundant. Here I offer my opinion of these products based on my use of them.
It was less than six months ago that I made the formal changeover to file playback from Redbook, and I am elated that I did. I don’t miss discs at all, which is amazing to me, considering how long I held on to playing them in the belief that I wouldn’t be able to achieve similar sound quality. Now, less than a year later, I’m blowing past the sound quality level I achieved with discs. With a DAC like the BMC PureDAC and even a server such as a stock Mac Mini I am getting better, far better, sound quality than I did with $10K players.
How can that be? Is USB playback that good? Yes, and it is especially good when the DAC is optimized for USB playback, as is the PureDAC. It may sound manifestly unfair to state that Redbook is not as good when the DAC being used is optimized for file playback. However, it’s not that the digital coaxial input of the PureDAC lacks (I checked it with my Musical Fidelity M1CDT Transport, which has shone brilliantly previously), but rather that USB can be optimized even as the same DAC chipset is used for both. Carlos Candeas, president and chief designer for Balanced Music Concept (BMC), related that Redbook has inherent limitations on how much can be obtained from the DAC chip set, while USB implementation can exploit functionality not available for S/PDIF, and this yields much greater resolution and clarity.
Carlos discussed with me, “The USB interface allows us not only to support all high resolution audio standards, but also makes us independent of a lot of computer weaknesses. We can create the digital audio stream within the PureDAC relying on our own time-base and even running the DAC and the USB synchronous.” Note what is being said; the DAC is not synched to the source, but is “asynchronous” to it, clocking itself.
A notable distinction between the S/PDIF (coaxial digital) input and the USB input of the PureDAC is that while the S/PDIF is upsampled, the USB input is not. According to Carlos, upsampling, “…processes the signal a lot and every solution known to me reduces the sound quality.” He explained the term oversampling, “… means a digital filtering creating an integer multiple of the original digital signal’s sampling frequency… It eases the requirements of analogue filtering a lot by putting the DAC’s noise spectrum far from the music signal.” Since the refreshed time base resides in the DAC the benefit that upsampling is intended to bring is no longer necessary, so it is eschewed.
A while back when I rolled opamps in the Eastern Electric Minimax DAC Plus I was informed by members of the online community that the real action was with discrete opamps, and they were right. Now, as I have seen comments on forums about the best digital being had via non-upsampling DACs I am being pulled in the direction of that conclusion forcefully by the performance of the PureDAC.
The USB function of the PureDAC accommodates DSD (64) and double DSD (128) format. Consequently, the owner while not necessarily “future-proofed” is current with the highest standards of file playback at an under $2K price point. This speaks to how dramatically digital treatment has improved and file playback component prices have plunged in the past five years. There are a slew of DACs being advertised in the audiophile magazines that can’t touch this level of performance, and I suggest you think twice before putting down your money on an alternative to the PureDAC that runs at 24/192 and upsamples.
- (Page 1 of 4)
- Next page →