The hires 24/96, 24/88.2, 24/176.4 or 24/192 files will be stored either in the laptop’s internal memory or an external hard disk.
With a DAC like the Rega DAC, you will encounter a major problem - how do you stream these hi-res files to the DAC without them being downsampled? This is because the USB input of the Rega DAC, like a few others in its price range, accepts only 16-bit/48kHz files.
And you will have a problem looking for a laptop - Mac or Windows-based - that has Toslink or coax outputs. Most Macs offer digital output via optical, but it is shared with the 3.5mm mini headphone jack and a normal Toslink cable cannot be plugged into it. So, if you own a MacBook, MacBook Pro, recent iMac or Mac Mini, you have to buy either a mini-Toslink adapter or mini-Toslink to Toslink cable to stream data via optical fibre to the DAC. However, the MacBook Air has no optical output.
This was the problem I faced. And I could think of only two solutions - borrow a USB/SPDIF converter like Stello’s U2 24/96 USB Link or Bryston’s BDP-1 digital music player to stream the hi-res files natively to the Rega DAC.
So I telephoned James Tan of AV Designs, the Malaysian Bryston dealer, and he said he would lend me the Bryston BDP-1 and the matching DAC next week.
Thus far, I can report only on how the Rega DAC sounds with 16/44.1 files streamed either from the resident Roksan Caspian CD player used as transport and ripped CD files streamed from a Toshiba laptop with Media Monkey.
I also heard 24/88.2 Studio Master FLAC files of Handel’s Messiah from Linn, but these were downsampled by Rega’s USB input.
I compared the Rega DAC with the Benchmark DAC1 Pre (‘warmed up’ with Furutech fuses and Siltech power cord) which was connected with a QED Toslink cable to the Roksan Caspian CD player. The Rega DAC was connected with an MIT Terminator 3 Coax cable to the 'Roksan.
The resident system comprised the Bryston 4B SST power amp, ATC SCM40 speakers, MIT Shotgun MA interconnects and MIT Shotgun MA biwire speaker cables with the entire system plugged to a Furutech eTP60/20 power distributor. I also used Sennheiser HD600 headphones to detect changes in the digital filter settings.
It is pretty obvious that the Rega DAC has a bassy sonic signature. This was especially so when the filter was set to number one (Rega recommends using Filter 1 - the linear-phase half-band filter - initially before you experiment with the other four settings when using different components).
The bassy tonal balance was at the expense of mid and treble transparency and treble extension.
|The Rega DAC|
Of all the filter settings, I felt that Filter 5 (minimum phase apodising filter) improved the mid transparency and treble extension the most and I used that setting for the rest of the listening session with 16/44.1 files.
It was when I streamed the 24/88.2 Linn Studio Master files through the USB that the Rega DAC’s weakness showed up glaringly. But to be fair to Rega, this is the same fate suffered by all DACs using a 16/48 USB input. When I tested Stello’s DA 100 Signature DAC (http://hi-fi-avenue.blogspot.com/2010/05/stellos-upsampling-dac.html), it sounded about the same through its 16/48 USB input.
I cannot confirm this, but the Rega DAC probably uses the same USB chip found in the Stello - the Burr-Brown PCM2704 from Texas Instruments which supports 16-bit files with 32, 44.1 and 48kHz sampling rates.
This flattened perspective pushed the images forward and the sense of spaciousness was much reduced.