Okay, let's break down this ambitious plan. Integrating your Magnepans with your ARK soundbar/sub and Sonos One surrounds is definitely "over the hedge," but potentially intriguing. Here's a look at the possibilities, pitfalls, and considerations

The Core Idea: Potential and Challenges
The Appeal

The allure is clear: you get to bring your beloved Magnepans into your surround sound setup. The Magnepans likely offer a wide soundstage and detailed presentation, especially with stereo sources.

The Challenge: Integration Complexity This is where things get tricky. Mixing speaker types (soundbar drivers with Magnepan planars) is fraught with potential sonic imbalances. Even with calibration, you may struggle to get a cohesive soundstage. Decoding & Routing

This is your most complex issue. There are many ways to go wrong here.

Points to Consider & Research ARC/eARC Compatibility and Soundbar Processing

This is your most crucial point. The Apple TV 4K will send audio to your TV via HDMI. Your TV must then send audio to your ARK soundbar via ARC (Audio Return Channel) or preferably eARC (Enhanced Audio Return Channel). Important: Ensure your TV's ARC/eARC output supports multichannel PCM or (even better) Dolby Digital/DTS bitstream. Many TVs can only output stereo PCM over ARC. If your TV limits the ARC/eARC output to stereo, your soundbar will not receive the surround information from the Apple TV. This will defeat the entire purpose of having surround speakers. Check your TV manual carefully. Your soundbar must be able to take the multichannel signal it receives over ARC/eARC and do the following:1. Extract the center channel information for its own drivers.
2. Send the front left and right channels to the Sonos Amp (which will then drive the Magnepans).3. Send the surround channel information wirelessly to the Sonos One speakers.
4. Handle the LFE (low-frequency effects) channel and send it to your subwoofer.

I seriously doubt the ARK soundbar is designed to do this. Soundbars are generally designed to handle the entire surround processing themselves and send the correct signals to their own drivers and any associated wireless surrounds/subs. Sending just the center channel information and somehow routing the front L/R channels out of the system to another amp/speakers is highly unusual. Sonos Amp Compatibility

The Sonos Amp can be configured to act as a standard amplifier for passive speakers. This part is straightforward. The trick is getting the correct signal to the Sonos Amp. You can adjust the Sonos Amp's output using the Sonos app. The Sonos Amp cannot be set up as center speakers.

Impedance Matching

Ensure the Magnepans' impedance is compatible with the Sonos Amp. Magnepans are typically 4 ohms, but some older models might be different. The Sonos Amp should handle 4-ohm speakers, but double-check the specifications.

Volume/Level Matching

Even with calibration software, getting the Magnepans to blend seamlessly in terms of loudness with the soundbar and Sonos Ones might be challenging. Magnepans are known for their detail and dynamics, and it's difficult to achieve a perfect match. The Sonos app has level adjustments for each zone, but it may not be enough to compensate for inherent differences.

Timbre Matching

This is the sonic character of the speakers. Magnepans sound vastly different than the drivers in the ARK soundbar or the Sonos Ones. This is the biggest hurdle to overcome.

Calibration

Your soundbar probably has some form of auto-calibration. Run this after everything is connected. It will attempt to adjust levels and delays to compensate for room acoustics and speaker placement. However, it won't magically make mismatched speakers sound identical.

How to Prototype and Test

Before committing to purchasing a Sonos Amp, I strongly suggest the following:1.

Thoroughly Examine Your Soundbar's Documentation

Read the manual from cover to cover! Look for any mention of the possibility of routing the front left and right channels to external speakers/amplifiers. I suspect you won't find it.2.

Contact ARK Support

Ask them directly about your proposed configuration. Explain that you want to use the soundbar only for the center channel and surround processing and drive the front L/R speakers with an external amp.3.

Simulate the Setup (if possible)

Do you have another amplifier you could temporarily use to drive the Magnepans? If so, experiment by splitting the signal from the Apple TV and sending the audio to both the soundbar and the other amplifier connected to your Magnepans. This will give you a rough idea of how the Magnepans will integrate sonically with the soundbar. You may find that the mismatch is simply too great.

Alternative Approach (and a more realistic one)

Instead of trying to integrate the Magnepans into the ARK system, consider using the Magnepans for a separate stereo listening setup. Use the Sonos Amp to drive them solely for music listening. You could switch inputs on the Sonos Amp to receive audio from the Apple TV for stereo music sources. This gives you the best of both worlds: a dedicated home theater system using the ARK setup and* a high-fidelity stereo system for music using your Magnepans.

In Conclusion:

While the idea of integrating your Magnepans is exciting, it's technically challenging and might lead to a compromised listening experience. Research thoroughly, prototype if possible, and be prepared to adjust your expectations. It's a project that could result in a truly unique system... or a sonic mess. Good luck, and approach it with careful planning and realistic expectations! Flag for review