Mark Levinson No.23.5 power amplifier:
Page 3 Don't get me wrong—the Levinson doesn't offer a flattened mid-fi stage. The horns on J. Gordon Holt's Praeludium recording on the original Stereophile Test CD are still set well back in the image, as indeed they should be. But it is possible that the No.23.5's somewhat more vivid balance overemphasizes recorded detail to the detriment of its depth presentation. Whether it is more or less accurate in this behavior is hard to determine with an electronic recording. However, those who desire the deepest of all possible soundstages should mate the 23.5 with loudspeakers that already excel in that area, such as the KEF R107. (This slightly dark-sounding speaker is also an excellent match for the Levinson's rather upfront tonal balance.) With the WATT/Puppies, however, the combination definitely produced a more shallow stage than was absolutely correct, both flute and piano on Stereophile's Poem LP moving nearer the listener than they had been at the original event, for example.

Comparisons
The first comparisons were performed with the more-than-twice-as-expensive, true class-A, Mark Levinson No.20.5 monoblocks. The stereo amplifier had actually more impact in the bass, something I would not have expected given the fact that the monos have fully regulated power supplies for their output stages. Nevertheless, the 20.5s were a little less well-defined in the midbass region. Soundstagewise, the two amplifiers were very similar in their depth presentation, though the 20.5s did sound a little more veiled throughout the midrange. The 23.5's presentation of detail was both more delicate and more comprehensive, meaning that instruments at the rear of the stage were more audible, while remaining about as far away. While still a superb amplifier, the No.20.5 would, I feel, benefit from some of the design thinking that metamorphosed the No.23 into the No.23.5

Next up was the obvious head-to-head competitor for the No.23.5, the $5900 Krell KSA-250. While each ranks among the finest solid-state amplifiers I have used, they still differed significantly in their sonic characters, meaning that a system set up optimally for one would need some adjustment to get the best from the other. In a nutshell, the Krell was less upfront in its midrange balance than the Levinson, sounding slightly "slower" and less vivid overall. It was also softer in both the upper bass and extreme highs, and presented a deeper soundstage. The Steinway piano on Stereophile's Intermezzo album was distinctly set more forward in the soundstage via the No.23.5 when compared with the KSA-250, with slightly less of a sense of the surrounding space. Microphone hiss was also a little more obtrusive in the top octave as presented by the Levinson. The Krell didn't quite achieve the dynamic contrast offered by the Levinson, however, nor was the piano's left-hand register quite as well defined. It would be a hard call deciding which amplifier was a better match for the WATTs and Puppies, the Krell offering a better balance overall but losing out to the Mark Levinson from the upper bass on down.

Comparing the No.23.5 with the similarly priced Goldmund Mimesis 8, the Swiss amplifier offered even more soundstage depth than the Krell and, when optimally set up, had a more musically neutral midrange than either American amp. It couldn't compete with them, however, when it came to bass reproduction: music combining complex scoring and high levels of bass energy sounded significantly more muddy on the WATT/Puppies when driven by the Goldmund.

The final set of comparisons was with the Audio Research Classic 60. Now it's true that the significantly lower-powered and less expensive tubed amplifier doesn't necessarily compete with the No.23.5 in the market, a more relevant comparison perhaps being between the solid-state amplifier and a pair of ARC Classic 120 monoblocks. But I'm very familiar with the Classic 60, and felt that as long as I didn't fall into the trap of describing differences that are purely due to the tube amplifier's more limited power capability, the comparison would be illuminating.

Despite the WATT's rather cruel impedance, which drops to 1.75 ohms in the low treble, the Audio Research drove the speakers to reasonably high levels from its 4 ohm taps. There was no doubt in my mind, however, that even at levels well below its clipping point, the Audio Research could not reproduce the music's dynamic contrasts as well as the Levinson. However, although the 60's low frequencies lacked the slam of the Levinson's, the leading edge of a kick drum's sound and the body of its tone was more in proportion via the tube amp, the "pat" and the "purr" being optimally balanced. In general, as described earlier, the Classic 60 offered a significantly deeper soundstage via the Wilson speakers, and individual instrumental images within that stage—the violin and piano in the Wilson Audio Beethoven Sonata recording (W-8315), for example—were more palpable, more "modeled" in the visual sense, as though the instruments were illuminated by a light placed more to the side than to the front. Tonally, however, the Mark Levinson had a little more midrange body with the Wilson speakers, which made the overall sound less lean/more neutral.

Conclusion
In many ways the burstproof, powerhouse No.23.5 is the best Mark Levinson amplifier yet to come from Madrigal Audio Laboratories. It offers a seemingly unlimited dynamic capability, superbly defined and extended low frequencies with all the speakers I used it with, and though it offers less soundstage depth than I think to be correct in absolute terms, this can be compensated for by careful choice of loudspeaker. Likewise, its rather forward upper midrange should not be problematic with loudspeakers that are not themselves similarly balanced. It proved a better match tonally with the KEF 107 than the Wilson WATT/Puppy, for example, though its sound driving the latter was never less than enjoyable, particularly in the authoritative manner with which it took hold of the system's mid–upper-bass region. Highly recommended—a true high-end amplifier.