Originally Posted by prozach1576
How is the experience of using this receiver with external power amps via the preamp outputs? Any hiccups? FWIW I'm not trying to do Atmos or anything. I want to use external amps for my full-range LR speakers in a 3.0 setup. Since this is the cheapest 4K receiver on the market with preamp outputs, I am thinking of snagging one of the refurbs before it's impossible to buy one.
Using external amps on an AVR's preouts is a very
common "upgrade" and there are zillions of forum posts about it. Often when you crunch the numbers, however, you discover that:
A) The increase in their maximum SPL output is often negligible [a trivial db or so, perhaps 2dB in some cases, and rarely a somewhat meaningful 3dB or more unless they invested in +200w/ch outboard amps.] PSST:
To learn what 1, 2, and 3dB changes sound like try moving your existing AVR's volume knob down and up by these amounts, as seen on the display's readout, to see what it means and if you personally deem the change significant in your
use. To calculate the change in maximum output level or "SPL at the listening position" a perspective outboard amp will achieve, try using an online calculator such as this one
which I find to be quick and easy (even though there are a few minor mistakes in the text descriptions outside this one's calculator section).
B) The customer often has increased their music's faint background noise [hiss] because they've increased the number of units in the signal path.
C) They've sometimes moved to an amp with an inferior signal-to-noise ratio as measured at 1 watt
[not to be confused with the more common full power SNR] hence they notice more faint hiss during the music's quiet passages [or at least if they press pause on their playback device and hold their ear close to the tweeter to listen to their system's rendition of "silence"].
D) They may not have the prerequisite conditions allowing for overall system gain factor optimization to keep noise as low as possible in a chain of devices. [Say if the outboard amp lacks a variable input sensitivity control and they lack the technical know-how of how to set things, ideally done with a meter and test tones.]
E) They've added the dangers associated with conducting the signal from one device to another via a wire [which can potentially act as an antenna to pick up even more noise along the way although usually this is not much of an issue in actual practice].
F) They escalate the potential for their system to take on a problem called "ground loop noise" because the new amp may have a different ground potential based on where it is plugged in [especially true if a different room AC outlet is used].
They also are spending hundreds if not thousands of more dollars, they consume more electricity, take up more room in their equipment rack, and generate more heat in the room so they have to turn up their AC.
People who are of the mind that all amps sound different and AVR amps are inherently "poor" [which I don't prescribe to] should do well with external amps especially if they don't test the net results using level matched, double blind testing to preclude expectation bias. If you think your system should sound better it often will [in your mind] due to the "placebo effect". But this doesn't mean in a forum with "science" in its title we should encourage abandoning evidence based science and instead do things based on group think.
I'm not saying there are never
any reasonable reasons to add external amps to an AVR, but much of the time when I see people do it the amps I often see they select offer very little "boost" over what they already have and they actually take on new potential problems like more system hiss and ground loop hum.
If you aren't finding your existing AVR is distorting on the loud musical peaks in the first place then you don't need more power.
[Since I consider this an important general topic I am starting a new thread with the above text.]
The preamp outs on these typical Yamaha's is not the greatest and is at a lower than ideal level so they will not work well on outboard amps without variable input sensitivity controls nor with amps with low amounts of gain, but the gripes I mentioned above apply to all
brands not just these Yamahas. Read more about the lower than ideal preamp output levels of a similar Yamaha from their upscale Aventage series here:
"At 1Vrms, the output looks much cleaner. If you're planning on using external amplification with the RX-A860, look for a power amplifier with a relatively high voltage gain (29dB or greater) so that it can achieve full rated power below where the preamp outputs of the RX-A860 starts clipping. For example, a 200-watt amplifier with a voltage gain of 29dB will reach its rated power at around 1.4Vrms."
P.S. I was dismayed to discover my TSR-7810, clone to the RXV781, lacks Dolby Atmos top/enabled channels despite the listing saying "full 7.1 preamp outs!" . Turns out you are locked to the 7 "bed" channels. [I had hoped to run experiments on the Dolby Atmos output through measurement devices, not use an external amp.] This won't be of concern to you for the front outs of course but I thought other might want to know.