Axiom Home Page Forums General Discussion Technical Questions A/V Receiver vs Amplifier

So I have been reading here and there...but a question remains. If someone has a 7.1 AV Receiver, ie. a Harman kardon...then why the need for a separate Amp. I guess my question is really....what are the benefits of having a separate amp (nad 7.1) plus a preamp? Just the amp power or is there something I am missing. My hk will do 120w per channel and that seems adequate...so why get a amp?

>>My hk will do 120w per channel and that seems adequate...so why get a amp?

In general, if 120w per channel is adequate (which it is for most systems) then you don't need an amp. There are a number of cases (some overlapping) where an outboard amp or amps can help :

1. You have a huge honkin' room and like to play really loud so 120w/channel is not sufficient.

2. In some cases 120w/channel is sufficient but if you run the receiver up in that power range for a long period of time it overheats because all that heat is being dissipated into one heat sink array. This is also why some people go for multiple amps -- a 5 channel and a 2 channel or a stack of 2 channel amps. A few people on the board have had to replace a 5 or 7 channel amp with a stack of stereo amps to get around heat problems. Yes I know this is hard to believe.

3. Also, if you are running up near the power limits of the amp that is where many people feel that you can start to hear differences in sound quality between amplifiers. We're not sure whether this is related to output impedence, "soft clipping", or something completely different but many people do report a significant difference when going from a receiver "driven hard" to a power amp with much more hearoom. You would probably get the same effect from a 300w/chan receiver, of course, if one existed.

Bottom line is that if you are not running near the limits of your current receiver then going to separates probably isn't going to make much difference. If you are anywhere near the power limits of your current receiver then an outboard amp can help.

Note that the easiest/cheapest first step is to offload the mains to an outboard stereo amp using the pre-outs in the receiver, leaving more headrooom for the remaining 5 channels.

I don't know if the processors have additional features/performance or if it's just cheaper to buy a good processor than a good high-end receiver (if you're not using the amps) -- all that stuff has been out of my budget for... oh, the last 20 years

Thanks BRIDGMAN.
Much appreciated explanation.
Now then if someone wanted a decent, not break the bank, amp to off load mains (new m60's which will take a few weeks to arrive) then what would you or anyone recommend?

i am budget conscious...especially after my huge axiom order. :-)

I imagine the Outlaw M200 monoblock (1 channel) amp is still the best bang for the buck. 200w 8 ohms, 300w 4 ohms, $299 new, $230 B-stock. You would need two, of course.

Probably best to wait for other replies from people who have actually BOUGHT an amp recently

The Oulaw mono is the option I think I will try first in looking for the same results.

This is a pretty basic article but...

http://www.hometheatersound.com/features/cinemacynergy/cc_20010901.htm

bridgman: good post!!!!!!!!!

Thanks to all Again.
I am looking at the Outlaw 200's for my front channels.
My only concern...my receiver HKDPr2005 or maybe AVR7300 has the auto level adjustment with a microphone built in to the remote. When using this type of setup how are the levels for the fronts adjusted....? Sorry for sounding idiotic....just want to make sure I understnad this. I saw the article and it was pretty clear and concise.

bridgman,
One should also add the idea about hard to drive speakers (not the M80s necessarily but speakers like electrostats). Many receivers do not support 4ohm loads, and even if they do it will tax a receiver more than a standalone amp (shutdown protection functions and such are still SPL dependant).
Not all amps can drive a 4ohm load either, but i believe there is alot more selection. For 8ohm speakers the selection for possible receivers increases dramatically.

Your receiver will adjust accordingly on its own with the outboard amps in place as long as you have it hooked up right.

Is there any reason not to get the newer hk635 if your going to add a couple of m200's?. You might save some coin this way.