The MRX 540 is a 5.1-channel A/V receiver with 5 channels of power and two preamplifier outputs, the MRX 740 is a 7.1-channel receiver with 7 channels of power and four preamplifier outputs, and the MRX 1140 is an 11.2-channel receiver with 11 channels of power and four preamplifier outputs.
The primary differences include the number of channels, preamplifier outputs, power output, and available features.
There are also differences with the supported subwoofer capabilities (The MRX 540 and 740 have two parallel outputs while the MRX 1140 has two independent outputs).
The MRX 540 also has less power output and does not have the amp matrixing feature, or Zone 2 functionality, while MRX 740 and MRX 1140 have varying amp matrix options with Zone 2 functionality available.
Please use the following links to review the features and specifications of the applicable unit:
MRX 540:
4K: https://www.anthemav.com/products-archived/model=mrx-540/page=overview
8K: https://www.anthemav.com/products-current/series=mrx-series-gen4-8k/model=mrx-540-8k/page=overview
MRX 740
4K: https://www.anthemav.com/products-archived/model=mrx-740/page=overview
8K: https://www.anthemav.com/products-current/series=mrx-series-gen4-8k/model=mrx-740-8k/page=overview
MRX 1140
4K: https://www.anthemav.com/products-archived/model=mrx-1140/page=overview
8K: https://www.anthemav.com/products-current/series=mrx-series-gen4-8k/model=mrx-1140-8k/page=overview