Tube Power Amp Reviews

Summary
So what's the bottom line, and what about all those tubes? First, from an operational standpoint, other than their considerable weight and even more considerable heat generation, the MB-750s were a delight. One of the annoyances I've lived with in my Ichibans—transformer hum—was thankfully all but gone. The main power transformer on one of the 750s did hum slightly, but not loudly enough to interfere with the music. Compared to the Ichibans, additional chassis damping and a more rigid structure have reduced the MB-750's susceptibility to airborne feedback and microphony, resulting in a noticeably lower noise floor. As for reliability, the MB-750s proved bulletproof through five months of heavy use. The bias on the output tubes was set when they were installed and checked every month thereafter—they've never varied more than about 5%. The factory suggests checking the bias no more than once or twice a year, which seems reasonable, particularly given that it's a real pain in the ass to do if you use the top chassis covers. No tube failures, no blown breakers, no problems of any sort.

The MB-750s' sonic performance was also beyond reproach. They succeeded spectacularly in all audiophile categories, but, far more important, they were fantastic for simply listening to music. I can't say that they were perfectly neutral, or that they vanished entirely from a system. They did have a subtle but distinctive character, shaded a bit toward the romantic, or warm and liquid, side of perfect transparency, with a slight emphasis of the mid- and upper bass and a slight rolloff at the very top. Similarly, they lacked the nth degree of refinement in their reproduction of low-level detail.

But I suspect that the MB-750s have been designed to have the specific character that they do, and to reproduce detail the way they do, because they sound exactly the way Luke Manley intended them to. Among the products that are as good as they can be today, these amps are "the State of the Art" in the truest sense of the phrase. In an imperfect world, even state-of-the-art products necessarily reflect their designer's selection of tradeoffs, the choices he or she has made in the attempt to create an illusion that leads the listener to a sense of reality. In the case of the MB-750s, it's a set of choices and compromises that I find consistent with live music, and that I would happily choose to build an audio system around. If I could afford to buy them, I would. If I can figure out a way to beg, borrow, or steal them, I will.

So when it's all said and done, just what does all that power do for you? In the case of the VTL MB-750s, it adds a dynamic punch and precision that injects music with more of the snap it has live. Sharp transients, subtle dynamic shadings, thundering crescendos—they're all reproduced effortlessly and accurately. Images are detailed without being overblown or over-etched; they're wonderfully three-dimensional, and firmly fixed within a soundstage and acoustic that draws the listener into the original space. What's more, regardless of the demands, no matter how complex the passage or explosive the crescendo, everything stays firmly in place without congestion, strain, or any perceptible change in character.

Trust me. You can't appreciate it until you've heard it, and once you've heard it, there's no going back. Now where's that Dave Bailey album...