When Mosfet power transistors were the 'new technology' most amplifiers that were based on these were proudly advertised as such. I always found them very 'screetchy' - especially when combined with metal dome tweeters.
Looking through amplifier specifications now I don't see them mentioned any more.
Is this because they are the 'de-facto' outputs stages now or that they have been discontinued in favour of the older bipolar outputs?
It's probably more likely that not enough people care. Listening to music isn't the same with the technology available now. Back then, it was kind of a breath of fresh air and the vast majority of receivers that were selling weren't really much to write home about, regardless of how many people are all nostalgic about them. MOS-Fets were a less expensive way to have a high power output amp for less money, they're self-limiting when they overheat, do better with high frequencies and tolerate more than regular outputs.
Ask 100 people who are looking for a new receiver if they think MOS-Fets are necessary and I guarantee that at least 90 will look at you like you have three heads.
