I have a Jon Soderberg upgraded S/150 sereis II. It is the lower powered one of the S sereis, but many thought it to be very Musical. It was rated at 90 watts but performs like much more.
Here is the proper website for Jon Soderberg.
http://www.vintageamprepair.net/
Here is the proper website for Jon Soderberg.
http://www.vintageamprepair.net/