I found the explanation below on the B&K Website in their FAQ's and think it's good. (I copied it directly from their FAQ - so credit to B&K).
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Question: What is a high-current amplifier and why is it better?
A high-current amplifier is capable of delivering power into low impedance loads (speakers)
without going into protection and/or shutting down. Ideally, an amplifiers output power would double
every time the load presented at its output is halved. For example, an ideal amplifier rated 250
Watts @ 8 Ohms would deliver 500 Watts @ 4 Ohms, noting that the load has halved and the
power has doubled. In actuality, a real-world high-current amplifier capable of 250 Watts @ 8
Ohms might be delivering about 425 Watts @ 4 Ohms.
An easy way to identify a high-current amplifier for use with home consumer electronics is
to look at what happens to the power rating as the impedance of its load (speakers) drops. The
closer the amplifier comes to approaching the ideal amplifier scenario, the more current the
amplifier is capable of delivering and the better the sound reproduced by the speaker.
In a typical amplifier-speaker circuit, voltage and current are delivered to a very complex load
consisting of speaker drivers, resistors, inductors, and capacitors. Voltage may be thought of as the
potential to do work, and current as what actually flows to do the work. Although basic power may
be calculated by the simple multiplication of voltage and current, it is the delivery of the power from
the amplifier to the complex speaker load that accounts for why two amplifiers may have the same
power rating into identical impedances (speaker loads), but still be significantly different from one
another in sound quality. Some of these sound quality differences may include perceived loudness,
depth, and clarity. Amplifiers that are designed to operate with high voltage as opposed to high
current are typically much better suited to high impedance loads, typically 8 Ohms and higher.
Lower current rated amplifiers have been said to sound dynamically limited and harsh at high
listening levels.
High quality audiophile speakers can have nominal impedances from 8 2 Ohms, and
during very dynamic passages in source material can easily dip below 2 Ohms. These super low
impedance drops can easily choke a high voltage amplifier with limited power storage capacity. For
a high-voltage amplifier, this will likely cause problems and trigger its protection, not to mention the
less than nice sound it may produce. A high-current amplifier operates with much less effort and
typically does not have any problem with these types of speakers.
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============================
Question: What is a high-current amplifier and why is it better?
A high-current amplifier is capable of delivering power into low impedance loads (speakers)
without going into protection and/or shutting down. Ideally, an amplifiers output power would double
every time the load presented at its output is halved. For example, an ideal amplifier rated 250
Watts @ 8 Ohms would deliver 500 Watts @ 4 Ohms, noting that the load has halved and the
power has doubled. In actuality, a real-world high-current amplifier capable of 250 Watts @ 8
Ohms might be delivering about 425 Watts @ 4 Ohms.
An easy way to identify a high-current amplifier for use with home consumer electronics is
to look at what happens to the power rating as the impedance of its load (speakers) drops. The
closer the amplifier comes to approaching the ideal amplifier scenario, the more current the
amplifier is capable of delivering and the better the sound reproduced by the speaker.
In a typical amplifier-speaker circuit, voltage and current are delivered to a very complex load
consisting of speaker drivers, resistors, inductors, and capacitors. Voltage may be thought of as the
potential to do work, and current as what actually flows to do the work. Although basic power may
be calculated by the simple multiplication of voltage and current, it is the delivery of the power from
the amplifier to the complex speaker load that accounts for why two amplifiers may have the same
power rating into identical impedances (speaker loads), but still be significantly different from one
another in sound quality. Some of these sound quality differences may include perceived loudness,
depth, and clarity. Amplifiers that are designed to operate with high voltage as opposed to high
current are typically much better suited to high impedance loads, typically 8 Ohms and higher.
Lower current rated amplifiers have been said to sound dynamically limited and harsh at high
listening levels.
High quality audiophile speakers can have nominal impedances from 8 2 Ohms, and
during very dynamic passages in source material can easily dip below 2 Ohms. These super low
impedance drops can easily choke a high voltage amplifier with limited power storage capacity. For
a high-voltage amplifier, this will likely cause problems and trigger its protection, not to mention the
less than nice sound it may produce. A high-current amplifier operates with much less effort and
typically does not have any problem with these types of speakers.
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