What is Subwoofer Pre-Out on an A/V Receiver? + When To Use It

Receivers can be complicated devices, and it’s easy to lose track of what specs and ports you need. One feature some subwoofers have is a Pre-Out can be especially confusing. If you’re looking into buying an A/V receiver, you may be wondering what a pre-out is and how to use it.

A subwoofer pre-out allows you to connect an external power amplifier instead of using the amp that’s built into the receiver. They can improve sound quality and distribution. Though it reduces strain on the receiver, it can consume more power and add more cables to your setup.

When you have a receiver, pre-outs can add valuable flexibility. That’s why this article covers various reasons why someone would use pre-outs on their A/V receiver, and both the pros and cons of using them. 

Key Takeaways

• Using Pre-Outs for Flexibility: Pre-outs in A/V receivers offer the ability to connect external amplifiers or active speakers, enhancing sound system power and quality, especially in large or complex setups. (Source)
  
• Pros and Cons: Using pre-outs reduces strain on the audio receiver and allows for advanced audio setups. On the other hand, they can increase power consumption, leading to higher expenses and more complex cabling needs.
  
• Usage and Setup: Pre-outs are common in high-end receivers and are relatively simple to use, providing connections for specialized speakers and enabling multi-room audio systems.

Why Would You Need Pre-Outs?

A pre-out is an audio output connection on an A/V receiver that sends a line-level audio signal, not amplified, to external amplifiers or active soundbars. This allows you to connect additional equipment to your home theater or audio system without using the receiver’s internal amplifiers.

A common usage of the pre-out is with a subwoofer. Subwoofers have their own internal amplifier, and it is often beneficial to use a pre-out connection. Some of the other reasons as to why would you need a pre-out are:

• To Connect External Amplifiers: Enhance the power and quality of your sound system, especially useful for large or complex speaker setups.
  
• For Active Speakers: Ideal for connecting speakers with built-in amplifiers, ensuring better sound quality and system efficiency.
  
• Multi-Room Audio Systems: Facilitate sound distribution to different rooms, using additional amplifiers for consistent audio quality.
  
• Reduce Receiver Load: Alleviate the burden on the receiver’s internal amplifier, potentially extending its lifespan and improving overall performance.

Note that this is a different conversation than preamps vs amps, which we unpack in a related post.

Benefits of Using Pre-Outs

By now I’m sure you understand some of the benefits a pre-out can offer you, but let’s look at some specific benefits.

Less Strain on Your A/V Receiver

Using pre-outs with an external power source has many benefits. The most obvious is that your receiver now has to use less power. The receiver’s built-in amplifier has a limited power supply and your speakers will benefit from sharing the power among fewer channels.

We advise it’s better to consider buying a higher-end model to avoid overloading. Moreover, better models are more equipped to handle Bluetooth via an adapter which we’ve explained before.

Our highly recommended Onkyo TX-RZ820 THX-Certified 4K Receiver (on Amazon), for instance, has pre-outs for 7.1 channels of sound. You can also look at our top recommendations for A/V Receivers.

Add Channels and Improve Your Speaker System

Another benefit is the ability to increase the capabilities of your surround sound system. Pre-outs make complex setups like Dolby Atmos possible and are necessary when many different channels are involved.

If your pre-out section has connections for speakers like “Front Wide” or “Height 2”, these are unique added channels that should be used with an external power source.

Pre-Outs Improve Sonic Character

When using pre-outs, both Passive and Active Speakers with their amplifiers will benefit. The overall sonic character of your system will be improved.

Cons of Pre-Outs

There are no free lunches when it comes to high-quality audio equipment though. Pre-outs can have their drawbacks.

Pre-Outs Can Be Expensive

If you’re looking to have a high-end home theater system, a more expensive A/V receiver will be necessary for your experience. Buying a powerful A/V receiver with plenty of options in the pre-out section is not cheap, but you get what you pay for. 

This can be a little discouraging when your shopping for a new receiver, since units like the Denon AVR-S540BT 5.2 channel 4K Receiver (on Amazon) can seem like a real deal until you go to expand them later, only to find there are actually no pre-outs.

More Amplifiers Means More Power Consumption

Another thing to think about when using pre-outs is the power consumption involved. Using pre-outs, like for subwoofers, increases power consumption since powerful A/V receivers and connected devices need separate outlets, leading to higher long-term costs for advanced home theaters.

Additional Cables and Potential Sound Issues

If you’re using most of the pre-out connections on your receiver, plenty of cables will be involved and things can get confusing. It’s always important to keep your cables maintained to prevent issues. If you need to plug in multiple items, check out our top ten list of the best surge protectors.

It’s possible that when using several different amps, slight inconsistencies may occur within your sound. However, these flaws would be so minor that virtually nobody will notice. But for a true audiophile, it’s possible that these sonic inconsistencies could be a disadvantage.

Are Pre-Outs Common on A/V Receivers?

Pre-outs have become quite common on A/V receivers, especially with higher-priced models. Each individual receiver will have different connections, so be sure to research your options before buying.

More expensive receivers will commonly have more connections than less powerful models. Some won’t include any pre-outs at all, but this is usually only with the cheaper models. Most A/V receivers on the market today include pre-outs. 

How do I Set Up the Pre-Out on My A/V Receiver?

Previously, we looked at how to connect a preamp to an AV receiver. Using the pre-outs on your receiver is a similarly simple process. First, identify if your speakers will be using the receiver’s amp or an external amp. For the speakers with an external amplifier, locate the corresponding pre-out connection on the receiver. 

When connecting your subwoofer via a pre-out, there are a few different connection options. A single tip RCA cable can be used, as well as an RCA cable and Y-Splitter if there are multiple sub ports. Some companies even offer a dedicated subwoofer cable.

Once your receiver and speaker are plugged in and connected, you should be ready to play audio. If you’re not getting any sound, double-check the connection you used on the receiver.

A Comparison: Sub-Out VS Pre-Out VS Line-Out

In this section, we will compare features like volume control, a signal type, and common use for sub-outs (also known as subwoofer-outs), pre-outs, and line-outs.

• Control Over Volume:
  
  • Sub-Out: Offers no volume control; it sends a specific low-frequency signal to the subwoofer, which has its own volume control.
    
  • Pre-Out: Provides more volume control flexibility, as the signal is unamplified and the volume can be adjusted by the external amplifier or active speaker it’s connected to.
    
  • Line-Out: Has no volume control; it sends a fixed-level signal to other devices, meaning volume adjustments must be made on the connected equipment, not the source.
    
• Type of Signal:
  
  • Sub-Out: Specialized for bass frequencies, enhancing the depth and quality of bass sounds in audio.
    
  • Pre-Out: Delivers a full-range audio signal, allowing for a broader spectrum of sound customization through external amplification.
    
  • Line-Out: Outputs a consistent, line-level audio signal, ideal for recording or processing without altering the sound quality.
    
• Application in Audio Systems:
  
  • Sub-Out: Specifically used for connecting subwoofers, crucial for home theater setups focusing on deep bass.
    
  • Pre-Out: Ideal for high-end audio systems where individual components (like amplifiers or active speakers) are used for a tailored sound experience.
    
  • Line-Out: Commonly used in professional audio setups, like studios, where the signal is routed to various equipment for mixing or recording.