NAIM: What value the mono switch?

For some reason or another I found the mono button on the Naim Nac 282 very useful on some rather rare occasions and clearly this facility is also available on preamps such as 252,552,32.5 etc. Now to get to the point of this thread I should like to know what other brands of preamps or integrated amps have this facility solely for my general info and of course they could be discontinued or even current models. I am sure some people will come up with some listings and indeed in fact some actual users of such preamps or integrateds.