Originally Posted by turnne1
By the way...I have to ask the question/make the statement as I have seen this mentioned several times
Why would anyone buy a receiver and then use it as a preamp only?
There are preamps available and always have been
As I understood it one of the advantages is to have separation of the heat from the amp and the other internal circuitry of the unit...further to this the more expensive units always seems to have better isolated components built into them
The issue comes up because the lower cost stand-alone processors' prices tend to start at $1500 or so and go up from there. An AVR model without the amplifiers but similar sound quality if you bypass the amplifiers may sell for $1000 or even less. The surround processor may carry some extra features like XLR inputs and/or outputs that the comparable AVR doesn't have - but the circuit boards inside may be the same circuit boards used in a less expensive AVR.
As you move into higher price ranges and non-Asian manufacturers, you tend to see processors that may not have AVR "brothers" - but if the company does sell an AVR, there's a good chance there's a lot in common between the AVR and processor. We assume a $2000 processor is going to be "better" than a $2000 AVR, but it may not necessarily be true if you bypass the $2000 AVR's amps. Now... if you are going to spend $2000 on a processor, you probably would go for the stand-alone processor since there's no reason to confuse things with idling amplifiers in a $2000 AVR. But if you can get a $1000 AVR that sounds as good as a $2000 processor... bypassing the internal amplifiers might sound like a great way to save $1000 since you are going to have the external amps for the $2000 processor anyway.
When I review an AVR, it is always helpful to know how the front-end performs and how the "back end" or amplifier section performs as separate entities even though few owners may ever use the AVR that way. But some enthusiasts on a budget might consider something like an AVR selling for, say $800 or even less if the front-end sounds great because their stand-alone processor options may not start until well over $800. They won't care about the amplifier sound as long as the front-end processing works well.
Something very significant happened with the sound quality of AVRs in general about 3 years ago - I still don't know what it is... but it is NOT digital amplifiers as the AVRs I find to have good-sounding amplifier sections don't have digital amplifiers. AVRs still can't control a speaker like a decent stand-alone amp... they just don't have the power supply capability to provide the drive capabilities, especially in the bass octaves, that you get from a good standalone amp. Of course, the whole AVR may cost less than a good stereo stand-alone amp... you do (often) get what you pay for in external amps. I have stereo amps here that have a transformer or transformers that weigh more than entire AVRs... and that's a key to getting superior current-drive and control capabilities. The sound quality improvement in AVR amps has been observed in AVRs with both integrated circuit amps and discrete transistors. I remain a non-fan of digital amplifiers, though some standalone high-ish-end digital amps are starting to sound pretty good.
Another AVR feature that had been appearing in more and more AVRs in recent years is the ability to assign amplifier channel in several different ways including bi-amplifying the front main speakers - this has made a HUGE difference in driving my reference speakers (Vandersteen 3A Signature nominal 6-ohm rating with 2 or 3 dips to 4 ohms or so). A single 125 watt AVR amp driving these speakers typically sounds very uninspiring but when these are bi-amped with good AVR amps, they sound FAR better... good enough that one could live with the AVR's amps whereas 4 or more years ago, an AVR in a similar place in the product line (no fair comparing an earlier top of the line model to a current middle-of-the-line model) would not produce sound that's very listenable.
If you are discussing top of the line AVRs ONLY... I don't see the big changes I've encountered in mid-priced and lower-priced models. Denon's top of the line hasn't changed much over the years, for example.