Question If I wish to use the M-One / M-One XL as a mono compressor+limiter for vocals. What are the recommended settings

You could recall a compressor algorithm in ENGINE 1 and a limiter algorithm in ENGINE 2. Also Choose the SERIAL Routing option in the Routing menu. Set the compressor so you get about 3 to 6dB of gain reduction maximum. You should check our new compression application booklet, where you can find tips on how to setup compressors. You will find it in the TC Tech Library. The threshold of the limiter you should set at -1dB so it will only hit the limiter just before it would clip. Although the M-One / M-One XL has compressor and limiter algorithms, for the insert application we recommend a dedicated compressor that has special presets and settings for this kind of application.