How To Connect A Car Amp To A Home Stereo (With Diagrams)

Using a car amp…at home? It’s not such a crazy idea after all! While it’s true that it’s not super easy, it’s really not all that hard and you can do it.

In this article, I’ll explain how to connect a car amp to a home stereo with clear diagrams anyone can understand. I’ll also show you all the little things you need to know before you try so you avoid disappointment & headaches.

First things first: Can a car amplifier be used at home?

Can a car amp be used at home man thinking

The good news is that YES, one way or another, you can definitely connect a car amp to a home stereo.

However, since car amps use a different power source the single biggest challenge is getting enough power to them. They also use a remote-on wire to turn the amp on & off so it doesn’t draw power and kill your battery when installed in a car.

Fortunately, these (and other) problems are fairly easy to deal with. Here’s a list of what you’ll run into when using a car amp at home:

  • Signal inputs: Not all home stereos have RCA line-level jacks, so this may require a workaround to connect to your amp’s audio inputs. Some amps make this pretty easy, however. (This isn’t much of a problem as you’ll see from my diagrams below)
  • Power source: Unlike home stereos that are powered from alternating current (AC), car amps work from a +12V direct current (DC) supply. You’ll need a +12V AC-DC power supply with enough current to run the amp. Not just any AC/DC 12V adapter will do as you’ll see later.
  • Turning the amp on/off: This is actually really easy! You can simply disconnect your DC power supply and let the amp shut off or use a simple switch to turn the amp on and off. I’ll show you how to wire the car amp so it can turn on.

The bad news is that unless you have the parts you need already, you’ll probably have to spend a little bit of money to get it working well.  The good news is that most of what you need can be found and bought new or used but you may need to order some online.

Sadly, retail stores are usually poorly stocked when it comes to power supplies that you can use for a car amp indoors. You’ll have much better luck online at places like Amazon or electronic parts suppliers.

How to use car amp with a home stereo + diagram

How to connect a car amp to a home stereo diagram

The way you’ll connect your car amp depends on both your home stereo and your car amp’s features as I mentioned earlier. You’ll end up with one of 3 situations:

  1. Home stereo with no RCA output jacks + car amp with speaker level inputs: It’s actually fairly common for home stereos and home theater receivers to have no full-range RCA jacks you can connect to the amp. In this case, if you’ve got a car amp with speaker level inputs these can be connected to either an unused pair of speaker terminals or alongside speaker terminals in use. The amp’s speaker level inputs will scale down the speaker inputs to a low signal it can use.
  2. Home stereo with no RCA output jacks + car amp with RCA jack inputs only: In this case, you’ll have no choice but to use a line level converter commonly used for car audio. Just like in #1 above, these are connected just like speakers to unused speaker terminals or alongside an existing speaker set. This will drop the signal down to a very low level that’s used by the amp’s RCA inputs. Note: I strongly recommend getting a decent quality model converter with adjustable outputs for best results.
  3. Home stereo with full range RCA output jacks + car amp: This is the easiest way by far, but not all home stereos have full-range RCA output jacks. Some only have subwoofer RCA output jacks which are bass-only outputs. Full-range RCA output jacks can be connected directly to the car amp’s RCA inputs.

How to connect the remote-on wire on a car amp

How to connect remote wire on car amp used in home diagram

In all cases, you’ll also need to wire the amp with power and a remote-on wire so it can turn on. You can do this one of several ways:

  • Jumper the remote on terminal:  When wiring the power and ground 12V connections, you can use a small jumper wire from the +12V terminal to the remote terminal so it’s on any time the amp has power.
  • Just a jumper wire + switch: Basically the same, but you can also duplicate how a car stereo’s remote on wire works by using a simple inline switch on the remote wire to turn it on/off yourself.

If you’re using a switch you can leave the AC/DC power supply plugged in if you like. When the amp’s remote wire loses its +12V signal, the amp will switch off internally and draw zero power.

Example of line level converter with remote wire output Axxess AX-ADCT2

QUICK TIP: To make things even easier, you can use a line level converter with a built-in remote wire output feature which will automatically turn the amp on or off with the speaker input signal.

Note that these do need a power and ground connection.

What is a line level/RCA converter and how do they work?

Image showing examples of line level RCA converters

Shown here are two examples of line level/RCA speaker level converters that work well for home receiver/amp to subwoofer use.

Line level converters (also called RCA speaker level adapters) are small electronic devices that connect to speaker outputs from an amp or receiver and scale down the higher-voltage signal to a low level (“line level”). The outputs are RCA jacks which can then be connected to an amplifier or subwoofer with RCA jacks.

They’re extremely handy in the car stereo world because they make it possible to connect a stereo without RCA outputs to any amplifier or powered subwoofer. We can also use them for home stereos, too.

How much do line level converters cost?

While you can get the el-cheapo ones for under $10, I don’t recommend those. Expect to spend around $15-25 or so for a good one. No need to spend too much these days as there are lots of good values out there.

What voltage & size DC power supply do I need for a car amp?

Example of how to estimate car amp current used

You can get a rough estimate of the maximum amount of electrical current you’ll need for a car amp using its maximum RMS power as shown here. However, if you’re not using an amp to its full capability you can get buy with a smaller (and less expensive) power supply.

What voltage does a car amp need?

Car amplifiers, when installed in a vehicle, work off of a voltage range as the engine runs. Although we say cars & trucks use a 12V supply, in reality, a car amp is designed to work from somewhere around 11V to 14.4V or so as the alternator in your vehicle raises or lowers it’s output while charging the battery.

Therefore you can use a power supply with a DC output similar to this, but I recommend 12V to 13.8V. Most power supplies you can buy are one of these.

What size power supply do I need?

Car amp DC power supply examples

You’ll need a power supply with a decent amperage (A) rating. Regular wall adapters won’t work as they’re very weak (0.5 to 1 amps or so). You can find 5A supplies for under $15 depending on where you shop. Desktop computer “ATX” power supplies are affordable and available in power ranges up to 500W or more. They’re easy to find but need a certain wiring connection in order to turn on.

In order to figure out how big of a DC power supply you need, you might want to calculate roughly the amount of current your amp will draw at full power. Once we know that, we can take into account wasted power that all amps use up and come up with a fairly accurate number.

Just so you know, class D car amplifiers are more efficient and therefore waste less power (and draw less current) than standard class A/B amps.

If you’re not sure what class your amp is, if it’s a class D amp it’s usually stated on the box or the amp itself. Class A/B amps often don’t state it anywhere. (Many new amps are class D so I wanted to take that into account)

Estimating amp current

You can estimate amp current based on the maximum RMS power of the amp. Don’t use “peak” or “maximum” watts as these don’t reflect the actual continuous power a car amp puts out.

As class D car amps are around 85% efficient and A/B amps are around 65% or so efficient we can use that to estimate the total current an amp would need.

Class D amp example:

Estimating the current used by a 50W RMS x 4 amp, all 4 channels used:

  1. 4 x 50W = 200W total. (200W/12V) = 16.7A.
  2. Take into account power waste: 16.7A/.85 = 19.6A
Class A/B amp example:

Estimating the current used by a 150W RMS x 2 amp, both channels used:

  1. 2 x 150W = 300W total. (300W/12V) = 25A.
  2. Take into account power waste: 25A/.65 = 38.4A

As you can see, to run a car amp at full power you’ll need a pretty big power supply! However, the good news is that it’s only if you really want to drive the amp at full capacity. For lower-power, casual listening, we can get by with a smaller (and thankfully, cheaper) power supply.

Realistic power ratings you’ll need

For just listening to music with decent volume, I recommend at least a 2.5A supply for small amps (under 50W/channel). For 4 channels or higher power ones, I’d get a 5 amp or bigger. If you’d like to have more power, consider getting 15A or above.

You can find a 5A supply for under $15-$20 if you shop carefully. 10A and 15A supplies are fairly popular so they’re usually really affordable, too. However, when it comes to much bigger supplies that will let you drive a subwoofer with heavy bass, for example, those can be expensive: $100 and above.

Connecting 2 RCA stereo outputs to a 4 channel amp

Diagram showing a 2 channel car stereo connected to a 4 channel ampWhat if you’ve got a 4 channel amp? No problem! You’ll still use the same methods shown earlier but you’ll need to jumper either the speaker level inputs or the RCA inputs using “Y” connections to get a signal to the rear channels too.

Most car amps with front & rear speaker level inputs can be wired to 2 speaker input pairs as shown in the diagram here. When using RCA connections, you can pick up a pair of inexpensive female-to-male Y adapters to split the signal from 2 into 4 connections. (Don’t spend too much on Y adapters as you can use a decent pair of cheap ones just fine)

QUICK TIP: Some car amps have a 2/4 channel input switch built in for this purpose. In that case, setting it to the “2ch” position will supply a signal to all 4 channels. For some amps this only applies to the RCA inputs so be sure to check your owner’s manual.

Can I use 8 ohm speakers with a car amp?

4 ohm vs 8 ohm speaker power comparison graph

This graph shows what happens when you use an 8 ohm speaker in the place of a 4 ohm one. The 8 ohm speaker will work – however, it comes with a price. Since the 8 ohm speaker isn’t matched to the 4 ohm car amp, it can only receive up to 1/2 the power output and has a lower maximum volume than a 4 ohm speaker would.

Using 8 ohm home speakers in place of 4 ohm ones with your car amp won’t hurt anything. There’s a catch, however. They’ll only develop 1/2 the power of a 4 ohm speaker meaning lower maximum volume is possible.

For example, if you were to use some home stereo 8 ohm speakers instead of 4 ohm speakers, you’d notice the volume would be a bit lower than when using 4 ohm ones. That’s because a speaker needs more and more power output to increase the volume more and more; also 8 ohm speakers allow only 1/2 the same amount of electrical current to flow vs 4 ohms.

Car amplifiers & car head units don’t have a high voltage supply like home stereos and home amplifiers do. That means they’re designed to use lower impedance (lower resistance) speakers to develop the same amount of power by letting more current flow.

As long as you’re aware of this it’s ok, because they’ll still sound and play fine – you just can’t get the same power and as much volume when you crank it up vs using 4 ohm speakers.

I have a hum (ground loop noise) from the amp. What can I do?

Example of an RCA ground loop isolator

Example of a ground loop isolator you can use to break the ground conductor connection in RCA cables to eliminate ground loop noise.

Unfortunately, noise is a problem with car amps despite them being designed to prevent it. It’s also true that home stereos and amps are known to sometimes create “ground loops” between different electronic components via the RCA cables.

Ground loop noise happens when there’s a slightly different potential (electrical voltage point) between the grounds of an amp, stereo, and other components. Despite everything you try, sometimes it’s nearly impossible to eliminate.

In that case, you can use a ground loop isolator to connect inline in the RCA cables. This usually does the trick. Note that you shouldn’t try to get the cheapest you find because they can negatively affect sound quality.

You can find a good one for $10-$25 or above depending on the brand and features. The good news is that they’re super easy to use: just connect them to the RCA cables and you’re done!

More great articles you’ll love

There’s lots more great stuff to see! Here are some excellent articles that have helped many others, too:

Your comments are welcome!

  1. Hi Marty! Great article, but I need some help. I had a MTX 801D amp and 2 Memphis 10″ subs that I decided to hook up to my garage stereo and i followed your article and bought a 12v inverter (linked below) and when I got it hooked up the amp it immediately started smoking. I used 4 ga cable for the + and – connected directly from the inverter to the amp. I also used a line output converter without the remote turn on so I jumpered that on the amp. I am baffled on how the amp immediately starts smoking and no fuses blow. The only thing I can think of is the amp may be bad. Your thoughts??

    Thanks!
    Zack

    Anbull SMPS 110V AC to 12V DC Converter Power Supply

    Reply
    • Hi that’s really unfortunate. It’s very difficult to say without more info, but one possibility is there’s a voltage issue somewhere and some components in the amp were damaged.

      Here are some possibilities, but of course they’re just “maybes”:

      • When connecting a power supply to an amp and a separate supply for a car stereo, the grounds should be connected.
      • You could also double-check the voltage out of the Anbull DC supply to be sure it’s normal as well as it could be too high etc.
      • Potentially something happened via the line level adapter

      Note that I’m assuming you mean you’re using separate supplies as you didn’t specify.

      You can have a voltage probably that won’t blow fuses because the fuses blow based on the current passing through them. The amp could be bad, but you’ll have to be sure before replacing it or it could happen again.

      Reply
  2. Hello Marty I am looking to add two 12’ planet audio subs with a planet audio amp to my existing Sony amplifier and 2 kenwood floor speakers. I will be buying a speaker wire to rca line out converter to hook up the amp to the amplifier I have. But I’m having trouble figuring out how to hook up the 12ac/dc power supply I want to go with example 2 in your article on how to hook everything up but I cannot find the right power supply to buy. So that I can power my amp I am good on everything else. Thank you for the help and if you would I would like to send you pictures of my setup as I am also a speaker junky

    Reply
    • Hi there, what type of trouble are you having specifically? It can take time to find one with a decent amp output rating, that’s for sure. You’ll have to live with some compromise since they’re simply not high-current like a vehicle alternator, but 30A and even 60A models are out there.

      If you need to you can message me directly (my email is on the Contact page).

      Reply
  3. Hello Marty I have a Sony in home sound bar and it also features a built in wired mini sub!! I have 2 12inch car subs and pioneer 900w amp is it possible to run the amp to the subs and still pull sound from the tv or Sony sound bar? Thanks

    Reply
    • Hi Hunter. Yes, that should be possible as long as you can get a signal to both. Generally speaking, it will be fairly easy using RCA jacks (or a 3.5mm headphone style jack) but you may need to go about it differently if you have other outputs available on the TV.

      Best regards.

      Reply
  4. Hey marty, I have a Dual SBX100 10” subwoofer and a Dual XPR522, and my goal is to get them wired into my guitar amp to I guess make a wheel around cabinet with a sub and amp, but I’ve found I need an amp to run the sun at the right levels but I’m unsure how to go about a power supply. I’m fine with something I might need plug in as well but the issue is finding the right power supply to run the ac/dc convert and run the amp

    Reply
    • Hello Levi. Well, there’s some information and examples in the article, but basically we’ll start by estimating how much current that amp would need.

      We can use the fuse (30A) on the amp as a guide, so if you want full power from the amp you would want close to a 30A capable power supply like those shown in the picture with examples. You can get a 12V switching power supply from Amazon or industrial suppliers with that rating or higher. Then you’ll just need a power cord.

      Reply
  5. Hey I am trying to hook up a home stereo receiver with a single subwoofer output to my car amp. With the amp powered but not connected to the receiver there is no hum. If I hook up the cable from the reciever to the amp I get a substantial hum, and no actual music or bass line?

    Reply
    • Hi that’s due to a ground loop carrying the 60Hz or 50Hz AC power “hum” as noise. You can try a number of things but it may just be easier to use a good quality ground loop isolator.

      You should be getting a signal however. You should also have a common ground between the car amp and the home stereo receiver as if not that can cause an issue too.

      Reply
  6. Hello Marty
    I need help please to buy right ac/dc power supply
    I have taken out of my car subwoofer alpine type x 12´´ 1243D and amplifier alpine pdx 1000.1 1000w but it doesnt say anywhere its class D amplifier. What is the best power supply for that please. Thank you for response ( want use it at home)

    Reply
    • Hello yes, it’s a class D amp as it’s listed in the specs for it I’ve seen. Most amps with that much power have to be class D these days anyhow.

      You won’t get full power without a very expensive power supply but you can get several hundred watts with a reasonably priced one. I would look for 30-50A 12V DC supplies at Amazon and other retailers online. Best regards.

      Reply
  7. Hello I am looking to see if what I have I am able to connect to my home receiver? I have a Denon AVR1312 home receiver that I want to connect to a Rockford Fosgate Power T1500-1bd amplifier and 1 Solo Baric L7 12” subwoofer from an old car setup I had. If this is possible can you tell me how and what I need to set it up and if not what can I change to make it work? Thank you.

    Reply
    • Hi you should just be able to use the subwoofer output jack on the receiver and an RCA cable + “Y” adapter similar the example #3 I provided. The rest of the info you need is in my article.

      Best regards.

      Reply
      • So I followed your directions and it worked but I’m getting a humming sound coming from the subwoofer when it plays. Do you know what this is and how to eliminate it?

        Reply
        • Hi Kyle. I cover that a bit in the article in the section about hum/ground loops. Ground loops can be an enormous pain in the behind to resolve but here are a few things you can try:

          – Have a common ground (very small wire gauge is fine) between the car amp and the home stereo.
          – Isolate the power supply on one of them. Isolated AC-DC supplies are harder to find, but you can sometimes find AC isolators you can use with the home stereo’s power.
          – Try running a small gauge jumper wire from the car amp RCA “shield” conductor (the round outside conductor) to different places like the home stereo’s metal case.

          A ground loop isolator is nearly guaranteed to fix the issue but if it’s not good quality it can hurt the sound quality. That’s because the miniature transformers used in cheap ones have a poor frequency response and will cut the bass and/or treble for example.

          There are some high-quality options out there if you want to go that route. If the home stereo has a digital output you can use an optical to RCA converter to do it also with perfect sound quality. They’re only about $25 these days.

          Good question and I’ll see about updating the article with these other ideas too. Thanks!

          Reply
          • Marty, thank you so much for all the good advice. Would this ground loop be the cause of the subwoofer hitting some notes well then cutting out all of a sudden then coming back on hitting some bass then cutting out again?

          • Hi, it shouldn’t be. It may be that you don’t have sufficient power available from the power supply you’re using and it’s dropping out or something similar.

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