Australian Hi-Fi

How to combine stereo and surround sound in one AV system

Your guide to building a best-of-both-worlds hi-fi and home cinema solution


So you’re lucky enough to have the space, money and marital understand­ing to set up a surround sound system at home. Fantastic news! But what about that hi-fi system you already own and love? Or what if hi-fi sound is just as important to you as those surround sound movies? The truth is that, when it comes to twochannel music, even the best AV amplifiers can’t hold a candle to the vast majority of stereo amps. And that’s why the general consensus has always been that you need to decide whether stereo or surround sound is your priority, and then sacrifice one for better performanc­e with the other.

But there is a way you can have your cake and eat it. If you have the money, appetite and a little bit of patience, building a system that includes both an AV amp and a stereo amp makes all sorts of sense. It’s not particular­ly difficult either, though admittedly it can be expensive if you’re starting from scratch.

What you need

The principle here is that you have two systems that meet in the middle but don’t overly impact one another. That means you need two amps; one for surround sound and another for stereo.

The AV amplifier or receiver needs to have pre-out sockets for the front-left and front-right speakers that bypass the unit’s own power amplificat­ion and output a pure, unamplifie­d analogue signal to the stereo amp, which can then amplify it. Pre-outs are pretty common on AV amps, no matter their level.

In theory, a system such as this can be set up with any stereo amp that has standard RCA inputs, but ideally you want one that has a dedicated input for the task — one that bypasses the unit’s own volume control and other equaliser functions. On integrated stereo amps, this home theatre bypass mode is commonly labelled as an AV input, though some also use proprietar­y names for the feature. For example, on Musical Fidelity and Rotel amps, the appropriat­e input is called ‘HT’. For Audiolab models, it is called the ‘Power Amp Input’.

Examples of excellent-sounding amplifiers with this function include (but are by no means limited to) the Audiolab 6000A, Musical Fidelity M2si, Moon 240i, Rega Elicit-R and Arcam SA30. Many brands, such as Cyrus, Naim and Musical Fidelity, go all-in on this feature across their lineups, too.

So why is this feature useful?

By bypassing the stereo amp’s own volume control, the AV amp is in complete control and has more sway when it comes to sonic character. All volume controls add a small amount of distortion and affect transparen­cy, too, so removing one is almost always a good thing.

If you’re set on using an amp that doesn’t have a dedicated AV input, you can instead set the volume control at the same level whenever you want to use it in tandem with your surround amp. That’s a more fiddly and less precise way of doing things, but it works just fine.

Of course, you also need speakers. Here, it makes sense to choose a surround package that includes front-left and front-right speakers with proper hi-fi credential­s, so we would start your search by looking for acclaimed stereo speakers — either standmount­s or floorstand­ers — that can be packaged up with a matching centre channel and subwoofer in the same range (or recommende­d by the retailer). Check reviews and forums that your choice works well as a whole package too, of course — synchronic­ity is key — but having quality front channels should put you in good stead.

It might seem obvious to say, but there’s no point in going down this route if you are only intending to use small satellite speakers.

How to set it all up

Once you have your AV amp and stereo amp, wiring is pretty straightfo­rward. Simply plug your front-left and front-right speakers into the terminals on the stereo amp, and all of the other speakers (centre, sub, surrounds and, if using, height speakers) into the relevant terminals on the AV amp. Then use standard analogue interconne­cts to hook up the front-left and frontright pre-outs of the AV amp to the AV input of the stereo amp.

Now you need to calibrate the speakers using the AV amp’s built-in, mic-driven set-up. In many cases, you’ll need to tell the AV amp the speaker configurat­ion you’re using, whether that’s 5.1 or 7.1, or even 7.1.4 for Dolby Atmos, but with many amps you won’t need to specify that you’re using the pre-outs at all. On some AV receivers, particular­ly higher-end ones, you’ll find an option called something like ‘amp assign’; use this to tell the AV amp that you’re using an external amp to power the front two speakers. Consult the manual if you’re not sure.

You should then be in a position to begin the automatic speaker calibratio­n as normal, checking that the test sounds are coming out of all speakers as expected, and that there are no error messages that might indicate a mistake in the wiring or amp assignment.

If you tend to watch movies alone on some occasions and with family or friends on others, I would recommend you carry out the calibratio­n process twice to create two ‘profiles’ to cater for both scenarios. That way you can set one soundfield up with a precise sweet spot in your listening position, and another so that your companions will also get a better experience.

At this point, you should have a perfectly balanced, volume-matched surround sound system — just as you would if all of the speakers were connected directly to the AV receiver. Now, connect all video sources (Blu-ray player, PS5, video streamer etc) to the AV amplifier as normal, and all two-channel music sources (turntable, CD player, music streamer etc) to the stereo amp.

The benefits

The major benefit here is a big one: because all two-channel sources are connected to the stereo amp, which exclusivel­y powers the frontleft and front-right speakers, they completely bypass the surround components. This is pure, unadultera­ted hi-fi — but then you also have a full surround sound system for a properly cinematic experience too.

Also, in some cases, by using an external amplifier for two of your speakers, your AV receiver’s own internal amplifiers can be directed to power other speakers, opening up the option for a surround system with more speakers. The newly announced Denon AVC-X4800H, for example, has nine built-in amplifiers (plus four subwoofer outputs), which you can deploy in up to a 5.4.4 configurat­ion. Take responsibi­lity for powering the front-left and front-right speakers away from it, though, and you could, for example, use those two ‘spare’ amplifiers to add two more Atmos speakers.

The drawbacks

One issue with a system such as this is that, while the auto-calibratio­n of an AV receiver is designed to balance the volume and tonality of di•erent speakers in a surround package — and will apply the same principle to the speakers being powered by the stereo amp — there are limits to what’s possible and some of the stereo amp’s character is likely to come through.

This can result in slight sonic inconsiste­ncies between the speakers running through the stereo amp and those that aren’t, which you might well notice — particular­ly across the front three. However, this can be minimised with judicious system matching and, for many, any slight flaw here is more than made up for by the purity of the hi-fi experience.

The other drawback here is price. Stereo amplifiers with dedicated AV inputs actually start at reasonable prices, but you’re still talking about paying that on top of the price of an AV receiver. Some may argue that if you have, say, $3,000 to spend on an audio system, you should get the best AV receiver or stereo amp you can a•ord, rather than compromise on both.

But there aren’t many AV amplifiers out there that do a really good job with stereo music.

And a two-channel hi-fi obviously can’t do surround sound at all. That’s why this best-ofboth-worlds approach is so appealing. If you have the willingnes­s to create a hybrid system to satisfy your music and movie needs, this is a recommenda­ble route to go down.

...choose a surround package that includes front-left and frontright speakers with proper hi-fi credential­s

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