"We also find the THX logo on powerful amplifiers, processors and integrated audio/video amplifiers, the latter being nothing less than a combination of the first two in the same box. A THX logo on an integrated audio/video amplifier indicates that the two parts of which it is composed: the amplifier and the processors, are both adapted to THX norms. For an amplifier to be labelled, it should, in short, guarantee a certain power, level of distortion and minimum rise time. In brief, nothing too difficult, and the hi-fi market is constantly pumping out amplifiers that exceed these characteristics, but it is also pumping out plenty that don’t… so beware! On the other hand, for the processor, the fact of being THX constitutes a certain advantage. Indeed, in becoming involved in decoding, there where a Dolby ProLogic or Dolby Digital decoder is limited to decoding, the THX procedure can bring in numerous advantages.
We have thus been able to note with pleasure that THX has brought an enormous amount of plusses to Dolby ProLogic, in granting it a veritable second youth. With devices such as Timbre Matching™, Decorrelation™, Re-equalisation™ and Bass Management™ Electronic Crossover, we have been able to totally rediscover entire films, benefiting from much more impressive dynamics and new effects – while these latter had in fact been encoded in the film, but never exploited to their maximum. This THX encoding optimisation has been named THX 4.0, because the Dolby Surround ProLogic only possesses four channels, right/centre/left/Surround and 0 channel of specific bass. New audio standards such as Dolby Digital and DTS have already resolved almost all the problems of our "good old" Dolby Surround, by offering an extraordinary dynamic, a total separation of channels, full band stereo in the rear speakers and a channel specially reserved for low frequencies. So… no further need for THX? Not so fast… THX was quick to return fire in creating THX 5.1, which is still there to ensure re-equalisation, "Timbre Matching", adaptive decorrelation, and to ensure that the end result is as good as George Lucas would have liked it.
Whatever the audio standard, THX will improve it, and if one was to classify audio standards by increasing order of quality, we would begin with Dolby Surround, then Dolby Surround THX 4.0, (that by which we all discovered what THX could do), followed by Dolby Digital, Dolby Digital THX 5.1, DTS and finally DTS THX 5.1."