It looks as though the PCBs are identical, or nearly so, but the 140 is de-populated compared to the 250.
The 28 black, squarish parts along the bottom edge of the 250's ADH board are (I think) each 4.7 μH inductors. These might be part of the class-D amplifier output, perhaps acting as a low-pass filter to convert the digital PWM output into analog.
The 140 seems to have fewer inductors (either 10 or 20 depending on what's inside the blue/grey packages), no doubt doing a similar job but catering for a lower output current. I can't read the part numbers to see what value the inductors have or how many there are per package.
The 28 black, squarish parts along the bottom edge of the 250's ADH board are (I think) each 4.7 μH inductors. These might be part of the class-D amplifier output, perhaps acting as a low-pass filter to convert the digital PWM output into analog.
The 140 seems to have fewer inductors (either 10 or 20 depending on what's inside the blue/grey packages), no doubt doing a similar job but catering for a lower output current. I can't read the part numbers to see what value the inductors have or how many there are per package.
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK
