John Atkinson, March 1995
JA compared the No.30.5 and Sonic Frontiers SFD-2 Mk.II in March 1995 (Vol.18 No.3):
My system consisted of B&W Silver Signatures driven by a pair of Mark Levinson No.20.6 monoblock power amplifiers; the preamplifier was first the Sonic Frontiers SFL-2, then the remote-controlled Mark Levinson No.38S. The digital source was a Mark Levinson No.31 transport connected to the processor via either Madrigal AES/EBU cable or ASM Labs' Mamba ST-optical cable. For reference purposes, I had the original SFD-2 and the Mark Levinson No.30.5. All analog connections were balanced, using AudioQuest's AudioTruth Lapis x3 interconnect.
I compared the new SFD-2 with the Mark Levinson No.30.5 with levels carefully matched using the No.38S's programmable volume control (footnote 1). for a while I found it difficult to home in on the exact sonic differences between these two leading contestants. After several discs, however, four consistent trends became apparent.
First, while the Mk.II SFD-2 sounded quite a bit more laid-back than the Mk.I, it still featured a somewhat forward balance in the upper mids. This was most apparent on pianoStereophile's Robert Silverman Concert CD (STPH005-2), for examplewhere the instrument acquired a more robust, louder-sounding presentation. By contrast, the Levinson presented the piano slightly behind the plane of the loudspeakerswhich, in itself, might lead the naive listener to assume that the recording was not playing quite so loud. This was also apparent on male voice. The lead vocal on "New York Minute," from the Eagles reunion album, Hell Freezes Over (Geffen GEFD-24725), sounded both more robust and more palpable over the Sonic Frontiers.
Second, the Levinson had fractionally more high-frequency air to its sound. While not something that would be identifiable in anything other than an A/B comparison, it made the recorded ambience sound more tangible. The Albuquerque church where I recorded Concert, for example, was just that little bit more identifiable over the No.30.5 than over the Sonic Frontiers.
Third, while the SFD-2's sound had more midbass body, the No.30.5's had more low-frequency extension. Kickdrum on the Eagles track was presented quite differently over the two processors: the Sonic Frontiers emphasized the midbass weight of the instrument; the Levinson emphasized its transient attackthe sheer kick-you-in-the-solar-plexus impactand had more ultimate low-frequency extension. I initially thought this might be due to the Sonic Frontiers' highish output impedance at low frequencies, but as the No.38S has an input impedance of 100k ohms, this shouldn't be a factor.
Finallyand, again, you must remember that I'm talking about small distinctions herethe SFD-2 had just a little more mid-treble grain than did the No.30.5. "History Repeats Itself," the Sara K. track featured on Stereophile's Test CD 3 (from Play on Words, Chesky JD105), allowed me to pick this up on the female vocal. There was a trace more sibilant edge to the sound of Sara K.'s mellifluous utterings via the SFD-2. Whether this is due to the Sonic Frontiers' 6DJ8 tubeswhich, in my experience, can introduce a bit of mid-treble glareor the fact that the SFD-2 uses a steel chassis, which will always have some deleterious effect on ultimate sound quality, I have no way of knowing. I can only wonder, however, what the already superb-sounding SFD-2 would sound like with a nonmagnetic, aluminum case.
Ultimately, for playback of non-HDCD recordings I preferred the three-times-the-price Mark Levinson No.30.5, which in my system sounded more natural/neutral. But in other systems, the nod might well go to the Sonic Frontiers SFD-2 Mk.IIas it did in Bob Harley's. However, when it came to HDCD playback, the SFD-2 outstripped the Levinson.John Atkinson
Footnote 1: Those who make a big deal about the difficulty of matching levels should note that all you need is a reasonable AC voltmeterI use a Fluke 87and the 20dB, 1kHz tone on the first Stereophile Test CD. Though the No.38S's volume control operates in 0.1dB steps, the fact that the No.30.5's output at 1kHz was almost exactly 2.4dB greater than the SFD-2's meant that any residual level error in my comparisons was below 0.02dB.John Atkinson