PDF schematic for a 2.1-channel power amplifier, meaning two satellite channels plus a subwoofer channel. The name does not identify the chips or the maker, so open the document to see the output stage, crossover and supply sections. Diagrams like this are handy when building a 2.1 amp kit or tracing a fault such as a dead sub channel, a hum or a failed output stage. The (2) suffix suggests another copy of the same file exists, so compare the two for revision differences.
The button opens the matching file on RM Schematics, or a source page if it is not catalogued there yet. The original attachment is from @pdf_servicemanual. Enginerys does not host this file.
How to open a .pdf file
The standard format for schematics, block diagrams, power-sequence charts and service manuals.