Originally Posted by orcrone
I have been looking to purchase an external amplifier to use with my Yamaha RX–A2030 receiver. I'm not convinced I will get an audible difference so I figure I will purchase something used. This way if I don't find much benefit or for doesn't last too long I'm not out that much money. And if I like the sound I am not out much money if I decide to purchase something bigger and badder.
My Yamaha is rated to put out 140 W per channel with only two channels driven. I've not found any specs that indicate the output with 5, 7 or 9 channels driven. On Craigslist I found it ad for an Adcom GFA-6000 amplifier for only $200. Its output is rated 100 watts/channel into three channels (left, center, right) and 60 watts/channel into two rear speakers. But those numbers are rated with all five channels being driven.
Do you think those amp numbers will make a difference versus what I have right now or should I look for something with more oomph?
If you look at my other thread I'm still considering the Adcom GFA-7607 which puts out 125 Watts per channel into seven channels
ACD (All Channels Driven) testing is not at all representative of the actual use of amplifiers to amplify audio signals related to music and drama.
AVS members are hardly alone in criticizing ACD testing. For example this well-respected group (Audioholics) uses the same facts to come to the same basic conclusion that ACD testing puts an unrealistic burden on power amplifiers:
"APC AV: I don't agree with testing All Channels Driven - it is not a realistic measure of anything useful. There is no standard means of testing with no valid data to support its veracity. I've never seen any data that says an ACD test is similar to the power consumed by a kick drum or T-Rex. I feel it is important that an amp be capable of driving all the channels at 1/3 or 1/X power concurrently and continuously without overheating or blowing up.
Common sense requires that an amplifier be electrically capable of supplying enough power to satisfy musical and theatrical dynamics without clipping. Therefore, a peak rating with a foundation in reality is also important, I want to know the amp is capable of supplying continuous and peak power to the speakers when needed."
Audio is supposed to be a fun hobby and if you define fun as having a power amplifier that functions well as a spot welder or is suitable for driving an industrial shaker table for destructive testing of military vehicles, then ACD ratings are right down your alley, and they should be your guide for buying.
If by some odd coincidence gear that does an excellent job of playing music cleanly is more consistent with your needs and you actually are so money conscious that you cash your income tax refund checks, then ACD power ratings should be way down your list of priorities.