The broader product idea originally pointed toward three TPA3255 devices and a higher channel count. This board uses two TPA3255s and four powered channels, with shared high-power distribution, Class-D switching, codec and DSP integration, mixed-signal layout, thermal concentration, startup control, and the ESP32-S3 control interface.

The four-channel board provides a platform for bring-up and refinement before any larger version.

Use ‘designed for four channels.’ Do not say the board produces or delivers 600 W. Mention the three-TPA direction only as a future or broader product concept.

The amplifier rail was not treated as one ideal 48 V node. It was divided into source, branch, capacitor, and amplifier nodes so resistance, path inductance, capacitor ESR and ESL, transient droop, resonance, and shared loading could be considered across the physical bus.

The same reasoning was also applied to the lower-voltage rails generated by the LMR38020, TPS62903, and TPS62913: load steps, regulator response, allowable droop, capacitance, ripple, ESR, and margin were considered together.

Say ‘modeled,’ ‘calculated,’ or ‘simulated.’ Do not say the bus is stable. Do not say a target impedance was met. Do not imply that capacitor values are experimentally optimized.

The amplifier bus needs significant capacitance. Connecting the Mornsun LMF1000-20B48 directly to the full downstream capacitor bank would create a large inrush event.

The TPS48111L-Q1 power-entry stage uses back-to-back MOSFETs and a resistor-limited precharge path. The capacitor bank required a controlled startup sequence, not just more capacitance.

Say ‘designed to limit inrush.’ Do not say inrush is solved or verified. Do not describe the design as certified protection. Do not claim reverse-polarity behavior unless separately confirmed from the schematic.

The mixed-signal layout was organized around expected current paths rather than simple ‘analog side’ and ‘digital side’ labels. The board combines Class-D switching currents, buck-converter hot loops, digital control activity, codec analog currents, USB transitions, and sensitive audio references, so placement and reference continuity were treated as system constraints.

The current direction is a solid ground structure. A more localized codec analog-return treatment is still under review, so the ground architecture is not final.

Do not say the board has a finalized split-ground architecture. Do not say return-current interference has been prevented. Do not say EMI or crosstalk has been solved. Do not show optional EMI footprints that are not on the board.

The high-current paths were treated as geometry, not only as nominal trace widths. Copper weight, layer, path length, neck-downs, branching, via fields, connector transitions, current crowding, and local thermal rise all affect whether a path that looks large enough on paper develops a resistive or thermal bottleneck.

This is also one of the main reasons the PCB is not yet being presented as finished. The final current-bottleneck and hotspot review may still move components, add copper, change neck-downs, or alter the power bus before fabrication.

Do not say current capacity is verified. Do not say the thermal design is complete. Do not treat a width calculator as final validation. Do not hide that copper changes may still occur.

The board was designed around an ordered bring-up process rather than the assumption that the complete system would power on and immediately pass audio. Power-entry behavior, low-voltage rails, clock access, reset release, control communication, codec and DSP initialization, and low-power amplifier testing each need observable intermediate states.

Current-sense shunts, clock access, adjacent rail and ground test points, and probe-friendly signal access are present in the design. The adjacent ground test points still need a larger footprint, and zero-ohm isolation or reconfiguration points still need to be added where they provide useful fault isolation.

Do not call any bring-up step completed. Do not imply firmware exists. Do not imply the clock, resets, or audio path have been observed. Present the sequence as the intended validation plan.

The board began as a possible answer to an awkward market gap between expensive integrated multichannel DSP amplifiers, limited-channel desktop amplifiers, and inexpensive bare modules with weak software and integration.

That product direction remained technically interesting, but detailed work on high-current magnetics, amplifier support components, power entry, protection, thermal hardware, PCB assembly, and integration made the original low-price assumption increasingly difficult to defend. The board is therefore best presented honestly as both a serious prototype toward that direction and proof of substantially more advanced system-level hardware design.

Do not promise a sale price. Do not claim production viability. Do not claim market validation. Do not present the board as commercially ready.