I have owned the st-150 and mb 450's The st-150 blew resistors once in a while. A pain because it weighs 75 lbs.
I have had no issues with my mb450's. they do not even run that hot. It is beautifully made. I will say the sound is amazing. It rules the speakers with an iron fist, but sounds smooth as silk. It ranks with the finest equiptment made . I think it is almost a bargan in the current used market. I also own tube amps from CJ and ARC and have had no problems ARC never even blows a resister when a tube blows. depending on how much you listen 6550 type tubes last around two years .
I have had no issues with my mb450's. they do not even run that hot. It is beautifully made. I will say the sound is amazing. It rules the speakers with an iron fist, but sounds smooth as silk. It ranks with the finest equiptment made . I think it is almost a bargan in the current used market. I also own tube amps from CJ and ARC and have had no problems ARC never even blows a resister when a tube blows. depending on how much you listen 6550 type tubes last around two years .