Hegel preamps volume control

Do the Hegel P20 and P30 preamps use relays for volume control or do they use a potentiometer for volume control and which is better?

I was looking at the Benchmark LA4 line amplifier which is relayed controlled and also at the Hegel P20 preamp but I cannot find any information about what kind of volume control is used on the Hegel, and which one is better and more reliable with a lower noise floor. Any opinions would be helpful and reasons for your opinion.