Quote:
Originally Posted by
commsysman
Let's just say that I don't know of very many 2-channel integrated amplifiers that are capable of driving a wide range of good speakers well for much under $1000.
For under $1500, some of the better integrated amplifiers that I would be comfortable recommending to a friend are the Creek Evolution 2, Arcam A19, and Musical Fidelity M3i.
The key spec that really tells you how well they can drive a speaker is the output impedance of the amplifier. That is what I look at first.
Amplifiers with an output impedance of less than 0.5 ohms can generally drive almost any speaker with minimal distortion.
With most speakers, 60 watts per channel at 4 ohms or more is usually enough IF the output impedance of the amplifier is low enough.
With very low-sensitivity speakers, less then 86 db/watt, of course, higher power may be needed.
The output impedance of the amplifier tells me a LOT more about how the amplifier will drive a speaker than a power rating determined by driving an 8 ohm resistor.
Interesting claim - that integrated amps with source impedances of less than 0.5 ohm are rare.
Let's give it a sniff test:
These are from Stereophile - the first 4 lab (random selection - not cherry picked) tests of SS integrated amps in their archives.
They are frequency response curves into 8,4, and 2 ohm loads, which can be used to discern amplifier source impedance.
We see that none of the amplifiers have significantly greater then 0.25 dB frequency response variation, which is typical of good modern SS amplifiers of any price.. They all show greater loss with lower load impedance (expected). 0.25 dB loss is about the same as 2.5% loss. We'd like to see response into a high impedance load (say 10,000 ohms) to calculate source impedance, but 8 ohms is so much higher than 2 ohms that we can estimate source impedance by saying that 8 ohms approximates a high impedance load. The source impedance of these (and any other good SS amp of any price including those in modern AVRs) is less than 1/40 (2.5%) of 2 ohms or 0.05 ohms.
The claim that integrated amps with source impedances of less than 0.5 ohm are rare is
not supported by readily available evidence
Unless we say
something crazy like "All good modern SS amplifiers sound the same", amplifier source is not a reliable indicator of amplifier sound quality. ;-)
***Yeah, amps 3 and 4 are a little weak but still beat the 0.5 ohm spec by a factor of 5), but I thought I'd keep you on your toes! ;-)***