What is Pass Through on an Amp?

"Pass-through" on an amplifier, particularly an AV receiver (AVR), refers to its ability to relay audio and/or video signals from an input source directly to an output device without processing, altering, or decoding them. This ensures the original, unaltered signal integrity is maintained, allowing downstream devices to perform the necessary decoding or display.

The Core Concept of Pass-Through

Imagine your AV receiver as a central hub for all your entertainment devices. When a signal is "passed through," it travels through the receiver to its final destination (like a TV or dedicated audio processor) without being stopped for internal processing by the receiver itself. This is particularly useful for modern, high-bandwidth audio and video formats.

For example, if you have a media player sending an advanced audio format like DTS to an intermediate device (such as a Sonos Port or similar audio streamer) connected to your AV receiver, "pass-through" ensures that the raw DTS bitstream is sent directly to the AV receiver. Your AV receiver, which is typically equipped with powerful decoders for multi-channel surround sound, can then decode the DTS signal and deliver the immersive audio experience through your speakers. This setup leverages the full processing capabilities of your main AV receiver rather than having an intermediate device down-convert or pre-process the audio.

Types of Pass-Through in Amplifiers

Pass-through functionality commonly applies to both audio and video signals:

1. Audio Pass-Through

Audio pass-through allows raw audio bitstreams to be sent directly to the AV receiver or another audio processor for decoding.

• Function: Instead of the intermediate source device (like a Blu-ray player or streaming stick) decoding the audio to a standard PCM (Pulse-Code Modulation) format, it sends the untouched, compressed audio format (e.g., Dolby Digital, DTS, Dolby Atmos, DTS:X) as a "bitstream."
• Benefit: This enables your AV receiver to perform the sophisticated decoding of these formats, taking full advantage of its multi-channel capabilities and advanced sound processing technologies to deliver the most authentic surround sound experience.

2. Video Pass-Through (HDMI Pass-Through)

Video pass-through, often referred to as HDMI pass-through, allows video signals to travel through the AV receiver to a display (TV or projector) without degradation.

• Function: High-resolution video signals (like 4K, HDR10, Dolby Vision, HLG) from source devices (e.g., gaming consoles, Blu-ray players, streaming boxes) are routed through the receiver directly to the TV. The receiver acts primarily as a switcher for these signals.
• Key Feature: Many modern AV receivers offer "HDMI pass-through in standby" or "HDMI standby pass-through." This crucial feature means you can watch video from a connected source (e.g., cable box, streaming stick) on your TV even when the AV receiver itself is turned off (in standby mode). This saves energy and simplifies operation when full surround sound isn't required.

Why Use Pass-Through? Benefits Explained

Utilizing pass-through features offers several significant advantages for your home theater or audio setup:

• Preserves Signal Integrity: The original digital signal is transmitted without unnecessary conversions or compressions, ensuring the highest possible quality for both audio and video.
• Optimal Decoding: It allows your most capable device (typically the AV receiver) to perform the complex decoding of high-resolution audio formats, leveraging its superior processing power and dedicated chipsets.
• Future-Proofing: As new audio and video formats emerge, a pass-through setup means your AV receiver can often handle them, provided it has the necessary decoders, without needing to replace intermediate source devices.
• Convenience: HDMI standby pass-through allows for watching TV without needing to power on the entire sound system, making everyday use simpler.
• Reduced Latency: Less processing by intermediate devices can sometimes contribute to lower audio/video latency, which is especially beneficial for gaming.

Common Scenarios for Pass-Through

Pass-through is fundamental to most modern home entertainment setups:

• Blu-ray Player to AV Receiver to TV: Both high-definition audio (e.g., DTS-HD Master Audio) and 4K HDR video signals are passed through the receiver, with the receiver handling audio decoding and acting as a video switch.
• Streaming Device to AV Receiver to TV: Similarly, streaming sticks or boxes send advanced audio and video formats that pass through the receiver.
• Gaming Console to AV Receiver to TV: Gamers often use pass-through to ensure minimal latency for video and to allow the receiver to decode multi-channel game audio.

Setting Up Pass-Through

Most modern AV receivers automatically enable pass-through for relevant signals. However, it's always a good idea to consult your AV receiver's manual and the settings of your source devices to ensure:

• Source device audio output is set to "bitstream" or "raw" (rather than "PCM" or "decoded").
• HDMI control features (like CEC) are enabled if you want seamless operation or standby pass-through.

Summary of Pass-Through Types