To enable this, create a smart collection named All Products and set the condition to 'Product price is greater than 0'. You can create a collection through the 'Collections' menu in Shopify admin. Or you can turn this section off through theme settings.
The MX600.1, MX1200.1, MX2000.1 are equipped with a variable 12db slope Lowpass crossover network and a 12db slope subsonic filter. The mono amps also feature a variable Bass Boost EQ is set at 45Hz.