Music in the Round #88: SPL Volume 8 and SMC 7.1 Did I Really Prefer SPL's Pro Devices to My Audiophile Preamps?

Sidebar: Did I Really Prefer SPL's Pro Devices to My Audiophile Preamps?

As a test, I did something I'd long considered trying but had always put off: I connected my exaSound e38 DAC directly to my power amps. This limits my choice of source components to my server, and to controlling the volume with only the up/down buttons on the exaSound's front panel, or an elusive little Apple remote control. What I discovered was that the effect of inserting each SPL box was almost inaudible. Maybe I perceived a little bit of softening of the highs, but no change in overall balance or resolution. Briefly—though only after a lot of cable-thrashing—I tried the same comparison with the Audio Research MP1 and the Parasound Halo P 7 and, dammit, they didn't sound much different either—but both, particularly the ARC, added some high-frequency noise.

That immediately reminded me of the phenomenon of stochastic resonance, which is often cited to explain why one can hear low-level signals that are below the noise threshold. Briefly, the principle is that subthreshold but salient signals, like music, become audible as concurrent frequencies in the random noise add to them. The ear can then distinguish the sum of the signal plus noise as a distinct pattern recognizable as the music signal.

I am positing that the ARC's audible HF noise works the same way to statistically emphasize higher audio frequencies that are below or above threshold. I can hear the hiss from my listening position when I turn the MP1 on, but my ears quickly adapt to it, and since it usually remains on, I'm usually unaware of it. That doesn't mean it isn't contributing a stochastic influence on the audible treble. I take it as consistent with my supposition that the much quieter but still not silent Parasound produced less treble emphasis than the ARC. Running the power amps from the exaSound e38 DAC or via SPL's Volume 8 or SMC 7.1 produced no noise from the speakers unless my ear was actually in contact with a tweeter.

Unfortunately for my hypothesis—from which I am not retreating—the published noise specs for the SPL boxes are not better than that for the Parasound, but they sound quieter than the Parasound or the Audio Research—although the exaSound e38 measures and sounds quietest of all. I just wish it had a volume knob.—Kalman Rubinson

Glotz's picture

I really wish Audio Research would produce an updated MP1 in the future. I thought that component was the most revolutionary product of that era. The way it brought instruments to the fore and still produced excellent depth of soundstage was a real ear-opener. The only way I could do surround, but obviously this product above would do much the same, only with less noise.

Kal Rubinson's picture

Agreed. For many reasons, I would much rather have an updated and quieter MP1 but that is not a real option.

retro's picture

Hello Kal!

Always enjoy your column..just wish they come more often..:)

You have compared more or less all the analog multichannel preamps. How does the tubed Fosgate stand up to the others, I know you reviewed one way back..?
Yes, I own one..:)


Kal Rubinson's picture

I was impressed with the Fosgate back then but it is just a memory for me now. At the time, I wanted to keep it but thought it beyond my budget. Today, frankly, I would not consider any tubed preamp in my system as I do not want any added flavor, sweet or not.

retro's picture

Aha, Mr. Rubinson don't like tubes..;)

Thanks for your reply!

Kal Rubinson's picture

Sorta but sorta irrelevant. There are no modern multichannel vacuum tube preamps to consider.

Mike-48's picture

Kal, Interesting reviews as always. Do you think the SPL Volume 8 sounded better over time because of warm up? Or the contrast to your system without it? And if the HF glint was gone, does that suggest the Volume 8 might be slightly rolled off? Or that its output drivers are smoother than those used before?