Why does Volt 876 have 32-bit A/D and D/A converters, while Apollo interfaces only have 24-bit?
Converter specifications are only part of the story. Apollo X Gen 2 specifications are the best overall in the entire UA interface line, and comparatively across the entire high-end interface market.
Is it true that 32-bit converters cannot be digitally clipped?
Generally, devices that cannot be clipped use 32-bit floating point converters. Volt 876 uses 32-bit fixed-point converters. With this in mind, you must still use proper gain staging to prevent digital clipping above 0 dBFS.
That being said, Apollo X Gen 2 and Volt 876 interfaces feature preamps with Assistive Auto-Gain to help with correct gain-staging to avoid digital clipping at the A/D converter.
OK, but I don’t get it - why do 32-bit converters exist, and why are they in the product if 24-bit converters have better specifications?
It’s a broader question of which ADC works best for a product, and how the ADC is implemented to meet a production cost-to-performance design. 24-bit or 32-bit does not automatically mean ‘better or worse’ when considered alone. Remember, ADC chips are only part of the story; surrounding components and circuit design are critical to the overall product performance as well.
Apollo interfaces have elite-class specifications and are designed with the absolute highest audio quality in mind. Consequently, they cost more to manufacture.
Nonetheless, Volt 876 has a remarkable price-to-performance balance, and its audio performance is broadly comparable to older Apollos from two and three generations ago, which cost far more than Volt 876.
New ADC chipsets often advertise 32-bit as a part of their design, with the theoretical dynamic range of 32-bit fixed point at 192 dB, or 144 dB for 24-bit conversion. However, we want to emphasize the theoretical part of these designs. In practice, actually achieving anywhere near that dynamic range in a real-world product is very difficult, if not impossible. Even with the difference in converters, Apollo x8p line inputs still offer 119 dB of dynamic range, compared to 116 dB dynamic range for Volt 876 line inputs.
To help you understand some of the terms in this and other articles, we have a glossary of terms available in this article.