Final Laboratory Music-4 phono preamplifier, Music-5 line preamplifier, & Music-6 power amplifier:
Page 2 Also of interest is the fact that the designers have chosen an input impedance of 560k ohms for the Music-4, which I'm told was motivated empirically and not as a result of some pet theory. That alone might indicate the use of a high-output moving-coil cartridge—not just because of the Music-4's lowish gain, but also because it might prefer to see a fairly high coil impedance—and owners of cartridges with drastically rising top ends will want to proceed with caution, if at all.

For its part, the Music-5 preamplifier—whose input impedance is an altogether more reasonable 50k ohms—is similar to its companion phono pre in both design and parts (more J-FET op-amps, more regulators-in-a-can). And it uses the same battery box as the Music-4, the Final Laboratory DC-5, meaning we're now up to 56 batteries—to the childless, a staggering number.

Which brings us to the brute of the family, the Music-6 amplifier: 10 big watts per channel, or a full 75% more power than I normally use with my ultra-efficient Lowther horns. As you might expect, the Music-6 requires a bit more in the way of juice; its companion power supply, the Final Laboratory DC-6, is actually a pair of battery boxes, each housing a series-connected bank of 18 D cells, for a total of ±27V. You might be able to get six months out of a set of batteries for the Music-6, but only if it's used with very efficient loudspeakers; as speaker efficiency goes down, so, too, does the life expectancy of your batteries.

The only active devices in the Music-6 are two heatsink-mounted op-amps, painted over in an apparent effort to conceal their identity. Op-amps, as a species, are designed to run at up to 100% negative feedback, and Final's designers have taken advantage of that fact by connecting a potentiometer between each chip's input and output and letting the user adjust the amount of negative feedback—and thus output impedance and loudspeaker damping—to suit his or her own speakers and taste in sound. Neat.

The parts quality in all three products is merely average by perfectionist audio standards, but Final makes a good case for favoring parts selection over pedigree: Given their minimalist (at least in the context of modern solid-state products) approach to voltage regulation and the obvious potential for continuously changing voltage conditions, it's easy to see how hand-matched parts can make a difference for the better. Inside the boxes, which are themselves nicely made, the quality of construction is only fair. The Final Music models are all hardwired (but not star-grounded), and most of the solder joints are bigger and blobbier than I care to see in an expensive product. Scant attention is paid to wire dressing, and board-to-chassis ground leads seem fragile.

Setup & Use
Setting up and using the Final system was fairly easy, once I got past the tedium of unwrapping and installing 92 flashlight batteries. Subwoofer owners will be disappointed that there is only one pair of output jacks on the preamp, but I suppose that's why every town has a RadioShack. User controls are good if mildly confusing: In particular, the Mute switches on all three products allow you to select between In and Out, but I often found myself having to remember whether it was the music or the muting that was getting switched "in"—a situation not helped by the products' counterintuitive pilot lights, which glow red when muted and go dark when music is being made.

On the other hand, I came to love the trim pots on the Music-4 and Music-5; they provide a handy way of effecting source-specific balance adjustments, and my voltage-droop paranoia was kept at bay with Final's built-in battery-check system. After three and a half months of frequent use, none of my battery boxes had drooped below their target voltage. Best of all, these amps didn't need to be warmed up. They sounded the same after two hours as they did after two minutes.

Listening
You can alter the Music-6 power amp's sound to suit your system simply by adjusting its negative feedback control: Changes made there were easy to hear, and musically and sonically influential. With my speakers, more feedback extended the power bandwidth toward both frequency extremes, but also introduced some unwanted texture or "grain," audible up top. It took only a little fiddling to find a setting that delivered a good sense of drive (the zero-feedback setting was as rhythmically slow and imprecise as it was sonically dull) while preserving the Final system's hallmark smoothness. And believe me, this system was nothing if not smooth—smooth, noiseless, and consistently easy to listen to.