A quick comparison is to check for frequency extremes, particularly highs & then, bass. To do this correctly you have to allow for the remaining system's faults / insufficiencies, and speaker set-up. (I.e. you might hear better articulated bass but if it's stronger it may excite room modes which are not the amp's fault)
Yes — a well-executed IC evaluation board can measure exceptionally well. That’s precisely its purpose: to provide a controlled reference platform for assessing the IC’s intrinsic performance and to serve as a baseline for system integration.
In fact, many cost-effective commercial amplifiers are essentially derivatives of these evaluation platforms, often enclosed in a chassis with some additional circuitry. This isn’t inherently negative — the performance-to-cost ratio of such designs can be excellent.
However, the resulting sonic character of an amplifier is not determined by the module alone. It’s a function of the complete electroacoustic system, particularly the interaction between the amplifier’s output stage and the loudspeaker load. Parameters such as output impedance, damping factor, load stability, and feedback implementation play a significant role in the perceived sound.
If possible, it’s highly instructive to compare different amplifier topologies in a controlled environment:
- GaN-based Class D designs (e.g., Atma-Sphere) — offering fast switching, low dead time, and potentially lower distortion.
- Purifi Eigentakt modules (e.g., NAD M33) — known for ultra-low distortion and load-invariant performance.
- Conventional Class AB designs using MOSFET or bipolar devices (e.g., Accuphase) — often valued for their linearity and established design maturity.
Good luck, the fun is in the quest!
