Flying Mole CA-S10 integrated amplifier
My first encounter with Flying Mole products was at Home Entertainment 2006, and I was impressed with their demo. Although I hadn't heard of Flying Mole before that, I found out later that it is not the tiny company that I somehow assumed that it was. Flying Mole amplifiers apparently have a considerable following in Japan, where, according to their website, the company's monoblocks were the fifth-best-selling amplifiers in 2005. The name of the company, which was founded in 2000 by some ex-Yamaha engineers, is said to represent "accomplishing the impossible by tireless efforts underground." Flying Mole Electronics' motto is "Resolution Revolution," and their products are said to be "in harmony with nature and are environmentally friendly." The CA-S10 ($2000) is the latest Flying Mole product to embody this philosophy.
Description and design
Flying Mole takes pride in making their amplifiers small. At roughly 11" wide, 2" high, 10" deep, and weighing less than 9 lbs, the CA-S10 is smaller and lighter than most preamplifiers, let alone an integrated amplifier with 100Wpc output. However, the expected relationship between size/weight and output capability assumes conventional analog amplification. The CA-S10 is one of the new breed of digital amplifiers: it has a switching power supply.
The design of the CA-S10 (described in some detail here) appears to be quite sophisticated, with careful attention paid to every aspect of the circuitry. The first thing to note is that the amp is not based on the ubiquitous ICE module from Bang & Olufsen (used by, among others, PS Audio and Jeff Rowland Design Group), but uses Flying Mole's own proprietary By-Phase PWM circuitry. The CA-S10 features dual-monophonic construction, with a high-power switching power supply. Both digital and analog negative feedback are used to eliminate sonic problems caused by AC voltage fluctuation. The CA-S10's overall efficiency is 85%, in line with Flying Mole's environmental concerns.
Flying Mole takes a minimalist approach to inputs, controls, and outputs. There are just three sets of RCA inputs, a pair of speaker connectors, and a source-selection knob, power button, and volume control (no balance). The speaker connectors take only banana plugs or bare wire (if it's not too thick), not spades of any sort. My favored Nordost Nirvana speaker cables use spade lugs; Nordost kindly sent me another pair of Nirvanas, equipped with bananas at the amplifier end.
Although the CA-S10's appearance and price are not those of a luxury product, its fit'n'finish are excellent, the brushed aluminum case suggesting a component costing well more than $2000. Still, near the end of my time with the CA-S10, when I pulled the interconnect from one of the input jacks, the ground part of the jack came out with it, and I could see no easy way of putting it back in. For the rest of my listening, I used one of the CA-S10's other inputs.
My Avantgarde Uno 3.0 speakers have a sensitivity of over 100dB and do not take kindly to noise anywhere in the system. When I introduced the CA-S10 into my system, the level of noise—mostly a kind of buzz, with hum components—was excessive. I've encountered this sort of problem before; the solution usually involves changing the grounding of components in the system. So I did that, alternately connecting and floating the grounds of the CA-S10 and the digital source components. Nothing seemed to make much of a difference. I even temporarily unplugged the Unos' powered subwoofers, to see if there was a ground loop involving the subs' amplifiers, but no luck there either.
In the past, I've found that preamps and power amps with noise problems usually sound better when plugged into one of the regenerated-AC outlets of the PS Audio P500 Power Plant power-line conditioner. No matter how good a preamp or power amp's built-in power-supply filtering, supplying it with the pure AC of the Power Plant can have only a positive effect—or so I thought. When I was trying the various grounding arrangements, the CA-S10 was already plugged into one of the P500's regenerated-AC outlets. Finally, I tried plugging the CA-S10 directly into an AC outlet in the wall—and, to my surprise, the noise was considerably lower in level (footnote 1). It was still audible from the listening seat when nothing was playing, but now the level was low enough to be masked by music played even at a low level.
Because I couldn't use the P500's normally superior regenerated-AC mode with the CA-S10, I thought perhaps I could try one of its Ultimate Outlets, which uses passive filtering. That turned out to be the best solution in this situation, the noise being slightly lower than when the CA-S10 was plugged directly into the wall outlet, and much lower than through a regenerated-AC outlet. I used that hookup for the rest of my listening.
Listening I: Break-in
Initial impressions of the Flying Mole CA-S10: great clarity, lots of detail, excellent bass, but an excessively bright tonal balance. Chesky's familiar Jazz Sampler & Audiophile Test Compact Disc, Vol.1 (Chesky JD37) sounded as if it had been remastered, with re-equalization that made the percussion instruments on track 3 have more presence than I'd heard before, but with an unnaturally edgy timbre that suggested synthesized versions of the real things. The DePaul University Jazz Ensemble's Big Band Basie (Reference RR63-CD), which I don't think was recorded with a particularly forward or treble-emphasized tonal balance, sounded similarly edgy, the trumpets having a piercing quality that went beyond what these instruments actually sound like in real life. Recordings that themselves have a bright, forward tonal balance, such as Christiane Noll's Broadway Love Story (Varèse Sarabande VSD 5956), one of my 1999 "Records To Die For," were virtually unlistenable at anything other than a background level. This was after all the changes in grounding described above; the Flying Mole was hardly "just out of the box."
So, was this what the CA-S10 "really" sounded like? Before accepting that conclusion, I had some alternative interpretations to consider. One possibility was that this was one of those components that take a long time to break in. The break-in phenomenon, though scoffed at by much of the traditional audio-engineering establishment, is well known to audiophiles, and I've had experience with components whose sonic characteristics changed significantly during the evaluation period. Some components sound much the same after several months' use as they do when first turned on; the changes, if they occur, generally involve a "relaxing" of the sound, the highs becoming less prominent, less forward. A second possibility was that the CA-S10 was interacting in a negative way with one or more of the components in my system. My experience with the CA-S10 "not liking" the balanced AC from the PS Audio P500 made me alert to this possibility.
I spent a greater-than-usual amount of time investigating these possibilities. First, I left the CA-S10 on all the time. This is not generally considered to be enough for break-in, but it can help. Then, whenever I left the house and there was no one else at home, I left the system playing at a fairly high level. I even dug out Purist Audio's The System Enhancer, a CD containing complex tones that are supposed to be particularly effective in facilitating the break-in process, and played it, on and off, for a total of about 24 hours. At other times during the evaluation period I tried substituting various components in the system: interconnects, speaker cables, digital front-end.
Judging potential changes in the sound of a system over a period of three months is a difficult process. In addition to changes in the sound itself, there is the possibility of the listener "getting used to" the sound—or, conversely, becoming aware of aspects of the sound that were previously not noticeable. Still, I'm reasonably confident in reporting that the sound of the CA-S10 did change during the evaluation period, and in the direction that I had hoped for.
Footnote 1: I told PS Audio's Paul McGowan about my experience, and the first question he asked was whether the amp I was using (which I did not identify) had a switching power supply. I told him it did, and he said that some amplifiers with such supplies "don't like" the balanced AC supplied by the P500. (Interestingly enough, PS Audio's own GCC-100 integrated amp has a switching power supply, and works just fine with power from a filtered or a regenerated-AC outlet.)