Bias determines the operating point of the tube without a signal applied i.e. just sitting there at idle. Some amps want the tubes to be just barely on. Some want them to be biased halfway on.
In most cases it is a simple procedure, some require a multimeter, some you turn a screw until an LED lights up (or just turns off), and many amps have automatic bias so you don't have to worry about it. Any reputable manufacturer should provide a manual with detailed instructions on how to bias their amp. If you are concerned you might want to start with an auto bias amp to see if tubes are your cup of tea.
Don't know enough about those you listed to comment.
In most cases it is a simple procedure, some require a multimeter, some you turn a screw until an LED lights up (or just turns off), and many amps have automatic bias so you don't have to worry about it. Any reputable manufacturer should provide a manual with detailed instructions on how to bias their amp. If you are concerned you might want to start with an auto bias amp to see if tubes are your cup of tea.
Don't know enough about those you listed to comment.