Originally Posted by SteveR1952
One of my options is the Integra DTA-70.1 amp at 150 watts per channel (two channels driven).
So in the real world of hearing sound reproduction does it make sense to go with a separate amp or just stay with the receiver or a more modest separate amplifier. Not looking to blast out my walls and I rarely listen to stuff at reference but my understanding was that some "excess" of wattage is needed for the amp to quickly output highly dynamic sound without taxing the amp. Am I off on this? If not, then it would follow that there is some desired amount of "excess" wattage per channel that should be resident in the amp. How much is enough? How much is a waste of money?
Thanks for the replies...I am learning as I go here.
You need 'enough' amplifier power. Anything more than enough is wasted. The tricky bit is deciding what is enough ;) The amount of amp power you need is a function of various things: the SPLs you want to listen at, the distance you sit from your speakers, the efficiency rating of your speakers being the most significant. All speaker manufacturers publish the efficiency rating of their speakers - it looks something like 86dB/1w/1m. This means the speaker will play at 86dB if you feed it 1 watt and measure it at 1 metre. For every 3dB you raise the required SPL, you need double the amp power - so if you want to hit peaks of, say, 105dB (the reference for movie sound reproduction), then, in this example, you would need an amp that can deliver about 65 watts. The further you sit from the speakers and the speaker placement in the room (close to walls, in or out of corners etc) also comes into it. The easiest way to determine the amp power you need in your room is to use a calculator like this:
You will also need to ensure that your chosen speakers can handle the power required to hit the SPL you want. Remember that you need to cater for peaks, not average SPLs, and you can be listening at 85dB average (reasonably loud) but you will need headroom to handle peaks of 105dB in my example. If you do not have the headroom required you will compress the dynamic range of the content (the ratio between the softest and loudest sounds) and/or you will run the amp into clipping. Clipping is potentially dangerous as it can cause your speaker drivers, especially tweeters, to be damaged. Clipping is caused when you ask the amp to deliver more than its rated power. (Rated power is quoted as xxx watts at a given level of distortion).
It is safe, and even recommended, that your amp can deliver rather more clean power than your speaker manufacturer specifies as the handling capability of the speaker. This means you avoid the dangers of clipping the amp when trying to hit those peaks and you will not harm your speakers by using an amp with good reserves of power. You will not 'overdrive' the speakers because your ears will readily hear any distortion caused by overdriving and you will turn down the volume accordingly.
Given all of the above, most decent modern AVRs can drive most speakers in most rooms to the levels most people want. The only way to know how much is needed in your specific case is to answer the questions posed above, use the calculator and then decide. If in doubt, err on the side of more power to be on the safe side. Also bear in mind that you may want to change your speakers in the future and you might want to make provision for less efficient designs or 4 ohm designs (some of the lesser AVRs struggle with 4 ohm loads).
The thing about a separate amp is that once you have it, it will last for decades. Receivers introduce new features annually, some of which you may want and some which you don't - but if you have a separate amp you can just install it and forget it - changing just the AVR used as a prepro) whenever necessary to gain new features - eg new sound codecs etc.