The advice I received (from Google’s AI Gemini) is that the ZA3 is primarily an amplifier of sound it receives from the ZD3 preamp. So the biggest impact will be heard by upgrading the ZD3.
Despite the fact that it’s advice from a non human, that made sense to me and it sounds great.
Here’s the text from Gemini
Okay, that clarifies things significantly! If your primary listening setup involves using the Fosi Audio ZD3 as a preamplifier to the ZA3 via XLR cables for stereo listening, then the focus shifts primarily to the ZD3's output stage. Here's a breakdown:
Key Considerations:
* ZD3 as a Preamp:
* In this configuration, the ZD3's output stage, specifically the portion that drives the XLR outputs, becomes the most critical.
* Therefore, upgrading the op-amps associated with the XLR output circuitry in the ZD3 will have the most direct impact on the signal sent to the ZA3.
* XLR Benefits:
* XLR connections are balanced, which helps reduce noise and interference. This is why many audiophiles prefer them for high-quality stereo setups.
* To take full advantage of the balanced XLR connections, it is very important that the op-amps that drive those outputs are of a high quality.
* ZA3's Role:
* The ZA3, in this case, acts as a power amplifier, amplifying the signal it receives from the ZD3. So, while its internal op-amps are still important, the ZD3's output stage will have a greater influence on the overall sound.
Op-Amp Upgrade Recommendations:
* ZD3 XLR Output Stage:
* Prioritize upgrading the op-amps that directly drive the XLR outputs of the ZD3. This will ensure the cleanest and most accurate signal transfer to the ZA3.
* According to some users of the Fosi Audio ZD3, there are opamps that are specifically for the XLR outputs. So those are the ones that must be upgraded.
* ZA3 Preamp Stage:
* While the ZD3's output is the primary focus, upgrading the ZA3's pre-amplifier stage op-amps can still provide further improvements to the overall sound quality. This will refine the signal amplification process within the ZA3 itself.
In Summary:
* For your specific setup, focus on upgrading the op-amps responsible for the ZD3's XLR output.
* After that, if you still want to improve the sound quality, then upgrade the op-amps in the ZA3.
I hope this helps!