amplifiers are susceptible to effects such as the ones noted here for the GFA-7807. It's just that these effects are much greater with the GFA-7807 than with other amplifiers we have tried so far. Other amplifiers also sonically benefit from being plugged into the same socket where their source component is plugged in, but the sonic difference and improvement is small in degree, not huge as we found it to be with the GFA-7807.
      For example, since we used the McCormack DNA-HT5 as a sonic comparison above, we thought it relevant to also check out the McCormack's susceptibility to these same ground circuit effects. The sound of the McCormack did improve slightly when it was plugged into the same wall socket as its source component, vs. being plugged into a different nearby wall socket. But the improvement was small in degree, not night and day as it was with the GFA-7807 (the McCormack became a bit more airy, with more open and extended trebles). We also tested and found a sonic difference with the McCormack when we connected a short custom wire between its chassis and the chassis of the signal source component, which we placed immediately adjacent to the McCormack. Again the difference was slight rather than major. But, interestingly, with the McCormack the difference was a clear improvement, whereas with the GFA-7807 the difference had been a clear degradation (with the two chassis intimately connected by this short wire, the McCormack's already excellent rendition of ambience and spatial air around each performer got even better). This suggests that the chassis ground circuit is better connected to the other ground circuits in the McCormack than it is in the GFA-7807.
      Thus, our suggested tactic, of plugging your power amplifier into the same power socket as the source component feeding it, can yield subtle sonic benefits with most power amplifiers, and yields a major benefit with the Adcom GFA-7807 that is crucial to hearing this amplifier at its best. Fortunately, this is a very easy tactic for you to implement with most system layouts. So you can enjoy the full euphonic magic of the GFA-7807 with very little extra effort. The only two peculiarities of setting up the GFA-7807 to hear it at its best are very easy for you to accommodate: simply use the unbalanced RCA inputs, and plug its power cord into the same (or immediately adjacent) power socket as the source component.
      Adcom also makes a five channel version of this amplifier, but we strongly recommend that you get the seven channel GFA-7807. Having at least one back surround channel is vital to truly convincing your ear/brain that you have been aurally transported to another spatial venue beyond your listening room, and that requires at least six channels of amplification (plus subwoofer(s)).
      The Adcom GFA-7807 is a triumph of engineering integrity, construction quality, powerful capability, and beautifully enjoyable sound, at an unbelievably low bargain price for so much product. If its euphonic transformation of recordings matches the sound you seek, this is the power amplifier for you. It can be justifiably used in a system with associated equipment that costs far more and is very revealing, so you can fully appreciate the GFA-7807's musical beauty and sonic prowess. Good job, Adcom!

GDV-850 DVD Player

      Adcom's GDV-850 DVD player has a sonic personality that's very similar to their GFA-7807 power amplifier. It furnishes a sonic portrait that's rich in warmth and bass, recessed in the upper midrange, and sweet and softly defocused in the trebles. When we inserted this DVD player into our lab reference system, which is neutral and very revealing, the GDV-850 created a very relaxing, enjoyable listening experience, from both music recordings and film soundtracks, very much like the GFA-7807 did. Clearly, Adcom's intent was to give this DVD player the same kind of euphonically enjoyable sound that they gave to their power amplifier.
      The GDV-850 is, however, not quite as excellent sonically as the GFA-7807 is. Even within the genre of their shared overall euphonic personalities, the GDV-850 had some objective flaws, to a seemingly greater degree than the GFA-7807. Most notably, the GDV-850 veiled and obscured some sonic information, compared to a reference quality DVD player, whereas the GFA-7807, though similarly softening and defocusing the sound, still managed to reveal sonic information (in this euphonically altered form) almost as well as a reference quality power amplifier. In other words, both Adcom units transform the personality of the sound, in the same euphonic way, but the GFA-7807 succeeds in still revealing most of the sonic information thus transformed, whereas the GDV-850 unfortunately veils and obscures some information that gets lost amidst or behind its softening transformation. Note that the euphonic transformation, wrought similarly by the GFA-7807 amplifier and the GDV-850 DVD player, is strictly speaking an objective inaccuracy, but we don't give demerits for this because this euphonic transformation, when done in just the right way and to just the right degree, serves well a higher goal of musically natural sound and sonic enjoyment. On the other hand, veiling is always bad and always gets demerits, because it simply obscures sonic information.
      The veiling in the GDV-850 is not as bad as the veiling we hear in many other audio components. The veiling in the GDV-850 does not, for example, have a raspy or ugly sound as we hear in some other products. Instead, the veiling in the GDV-850 is the aural equivalent of putting a gauze curtain between you and something you're looking at. The gauze curtain not only softens the visual image you get, but also softly smears and obscures details of what you're looking at through the curtain. Aurally, the GDV-850 puts this gauze curtain between you and the sonic details of the recording. Its soft, gentle obscuring of subtle details also adversely affects its stereo and surround imaging. Some of the subtle cues that exactly localize various sonic events in the surround soundfield are obscured by the GDV-850, so localization is not as defined and precise as it is from a reference quality DVD player (such as the Arcam DV-27A).
      Now, the GDV-850 costs only $1000, compared to about $3000 for most reference quality DVD players. In this context, the sound of the GDV-850 is acceptable, and does a credible job for the money. Because its sonic veiling is soft in nature, you won't really be aware of it, and you won't miss the sonic information you're not hearing, unless you compare the GDV-850 directly with a reference quality DVD player.
      At its modest price, the GDV-850 also fails to include some of the bells and whistles that more expensive DVD players include. For example, some reference quality DVD players include volume level controls for individual channels, and wide ranging delay adjustments for the various groups of channels. These extra controls enable you, if you wish, to run these reference quality DVD players directly into your power amplifiers. Thus, these reference quality DVD players give you double sonic advantage: better intrinsic sound, plus the ability to get even better sound by running their signal directly into power amplifiers, thereby bypassing the sonic degradations of having to go through a processor's controls. On the other hand, the GDV-850 gives you a double sonic disadvantage: slightly veiled intrinsic sound, plus forcing you to go through a processor to control volume and obtain wide ranging delay control, thereby degrading the sound even further.
      Only you can decide whether this modest degree of sonic compromise is acceptable to you, in exchange for saving $2000 off what a reference quality DVD player might cost. The sonic performance of the GDV-850 DVD player is certainly reasonable for its price. But then you also have to consider the competition. And, interestingly, the GDV-850's most potent competition comes from Adcom itself, and from a very surprising quarter. How so?
      If we were in your shoes, and wanted the kind of euphonic sound that the Adcom GFA-7807 power amplifier provides so well and that the GDV-850 DVD player also provides, we would choose the Adcom power amplifier over the DVD player, and get a different DVD player. Why not choose both these Adcom units? Because, when you stack two of these "just right" euphonic transformations in series, they add. A double dose of this euphonic transformation is no longer just right, but instead becomes far too much of what was a good thing.
      A single dose of this euphonic transformation puts music and sonic events at a distance, a distance which realistically mimics the distance you experience live from an audience seat. But a double dose makes music and sonic events sound much too heavy, dark, and far away, as though they were at the far end of a long, dark tunnel. When we inserted either the power amplifier or the DVD player alone into our lab reference system, the euphonic transformation was excellent in nature and degree. But when we inserted both units into our reference system, the sound became much too dark and far away (with the upper midrange being doubly recessed), too fat and warm (with a doubly rich dose of bass and warmth), and the music and sonic events sounded as though they were not in the same hall or space where we were, but instead were at the far end of a dark tunnel. We even tried using reference quality links elsewhere in the system that if anything are a little bright and lean (to make sure that we were not introducing any of this dark coloration via any other system link), and the sound still became much too dark and distant when we employed both Adcom units instead of just either one or the other. So we would recommend using both these Adcom units only in a system that included some sonically offsetting links that are very lean, very emphasized in the upper midrange, and hard sounding (there are indeed some loudspeakers like this).
      We would pick the Adcom GFA-7807 power amplifier over the GDV-850 DVD player to perform this euphonic transformation because it is so sonically excellent, and so capably powerful, and it does not have the slight sonic compromises that the GDV-850 DVD player has. Also, when you think about it, the Adcom GFA-7807 is an even better bargain, since it saves you $7800 compared to what a similarly sounding Plinius Odeon would cost you, while the GDV-850 DVD player only saves you a measly $2000 compared to a reference quality DVD player. Of course, if your budget can't afford this extra $2000, you'll want to get a DVD player that, like the GDV-850, is about $1000. A competing DVD player in the $1000 bracket will surely have its own slight sonic compromises, with pros and cons compared to the GDV-850's slight sonic compromises. But, if you plan to buy Adcom's GFA-7807 power amplifier to get that wonderful euphonic transformation, then you should pair it with a DVD that is tonally neutral and which does not, like the GDV-850, also execute this tonal transformation.
      On the other hand, if you now own a tonally neutral power amplifier that you want to keep, and would like to hear this euphonic transformation that we have described and praised so highly in the Adcom GFA-7807 power amplifier review, then the Adcom GDV-850 DVD player gives you a great entry point, at just $1000, to get this euphonic transformation into your system.

Video Quality

      In my judgment, the video of the GDV-850 is passably acceptable, but noticeably below reference quality. The picture can be set to have plenty of vivid punch at the dynamic extremes of luminance, hue, and color saturation, so some viewers would probably be impressed. But I see a lack of subtle discrimination among midrange values of luminance, hue, and saturation. As a result, relatively large areas or patches appear to have the same uniform look, with exactly the same midrange value of luminance, hue, and saturation.
      For example, an area of human flesh, such as the cheek of a person's face, in reality has a myriad of subtle variations over every square micron of that flesh, variations in luminance, hue, and saturation - variations that when properly reproduced by a video system make the flesh look real. I see these myriad variations over every square micron, in a human face or cheek as portrayed by a reference quality DVD player (e.g. the Arcam DV27A). This allows the flesh to look believably real, and also three dimensional, because I can see the subtle imperfections marking the texture of the surface (the depressions of its pockmarks and its pores), and I can also see the subtle variation in shading that marks the three dimensional contouring of the cheek (especially under good movie lighting).
      But the same large area of face or cheek portrayed by the GDV-850 lacks these myriad variations, and instead appears to be a single patch or area of completely uniform luminance, hue, and saturation. The result is that a person's whole cheek appears to be uniformly painted, as in a cartoon or as with pancake makeup; and furthermore appears to be only a superficial surface, lacking the texture and depth of pockmarks and pores; and furthermore appears to be flat and two dimensional, because the subtle lighting variations from contouring are missing. Thus, with the GDV-850 I get the visual sense that I am watching a cartoon instead of real characters, or that the movie's makeup artist used pancake too heavily, or that the movie's lighting director had no talent for lighting faces to get realistic contouring.
      Likewise, landscapes and cityscapes look more two dimensional from the GDV-850, with less three dimensional depth than I see from reference quality DVD players (e.g. the Arcam DV27A). As you may know, the three dimensional quality we see in real life landscapes and cityscapes arises in large part because air contains haze and air scatters light, so that progressively more distant mountains and buildings appear slightly hazier, slightly paler, and slightly less distinct. These subtle natural variations with distance, that give three dimensionality to real landscapes and cityscapes seen live, require a video system to be able to reproduce subtle variations in the midranges of luminance, hue, and saturation. When a DVD player like the GDV-850 does not do this adequately, then there is not sufficient discrimination in the visual progression from near mountains to middle mountains to far mountains (or near buildings to middle buildings to far buildings), and so the whole scene collapses into a shallower depth, becoming flatter and less three dimensional.
      The two most important elements in most films are the people and the scenery (or set). If the people look real then you can believe in them, and if the scenery looks real then you can believe in where these people are and in what's happening to them. If you can believe in just these things, then you have achieved that magic suspension of visual disbelief that is crucial to that ultimate goal of truly enjoying the movie experience, feeling that you have been transported out of your room and to the venue of the film. But if the people look like cartoon characters or flat faced caricatures with too much pancake makeup, or if the scenery looks shallow and two dimensional, then you can't believe in the portrayed reality of what you see, and you'll never experience the magic. And that's why subtle resolution in the midranges of luminance, hue, and saturation is so important (even more important than the specsmanship of black levels and contrast ratio that merely describe the extreme ends of video parameters).
      The GDV-850 allows the user to freely manually select between the two international black level standards (some other DVD players automatically make the correct black level choice, for your designated country and video standard). Curiously, we found that neither black level yielded an optimum overall picture.
      We directly fed the GDV-850, via Nordost Optix cable, into a Princeton CRT monitor that had been calibrated with and gave excellent pictures with other DVD players. But the GDV-850, at its low black setting (0 IRE, for Japan), exaggerated picture contrast too much (toward the luminance extremes), and exaggerated color saturation too much (too cartoonishly saturated). On the other hand, at its high black setting, the normal 7.5 IRE, the GDV-850 pulled in the luminance extremes too much, yielding a picture with too little contrast, and under-saturated color, making all colors too bland and pale.
      The video norm for these contrast and color saturation extremes, as exhibited by most other high quality DVD players, was about halfway between the two behaviors exhibited by the GDV-850, at its two settings of black level. Thus, if you get a GDV-850, you would have to pick one black setting and then re-calibrate your display to notably different settings than you would be using for other high quality DVD players.
      Furthermore, even though the GDV-850's several video extremes were very different at these two black level settings, the GDV-850's other video flaw discussed above, lack of adequate discrimination in the video midranges, was still observed in both these black level settings. This suggests a far too low gamma setting in the GDV-850. You might think that you could simply compensate for this by adjusting the gamma level of your display to be above normal. But this is not so.
      Most displays (other than CRTs) intrinsically have a gamma that deviates from the logarithmic ideal, so the electrical circuitry in a competent display needs to compensate for this, by controlling gamma in a nonlinear fashion (with respect to the ideal logarithmic curve), giving different amounts of compensating gamma boost at different luminance levels. Then, the gamma adjustment control for such displays should work with and control the actions of this nonlinear compensating circuit, so that the gamma adjustments wrought by this control are tailor made for the nonlinear needs of the intrinsic display. Such a nonlinear gamma adjustment control, tailor made to be optimal for compensating the intrinsic display characteristics, would not of course be optimal for adjusting gamma in (say) the linear fashion needed to compensate for a (presumably) linear gamma error earlier in the chain, e.g. from the DVD player. Also, many displays might economize by simply making their gamma adjustment control part of their gamma compensation circuit,  rather than going to the extra expense of providing a whole separate stage just for linear gamma adjustment.
      In other words, the gamma adjustment for such displays might be suitable for optimally compensating the intrinsic gamma of the display itself to be calibrated with respect to the standard of a 2.20 logarithmic slope, but it may not suitable for compensating for a too low or too high gamma in an external source device such as a player, especially since the shape of the player's erroneous gamma curve will almost surely be different than the nonlinear curve built into the display's compensating circuitry of the gamma adjustment, for a particular type and brand of display.

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