IMHO, the 150A is a much better amp than the older 250.
The 150 came in an "A" version and a HOT ROD version in addition to just the regular 150 original issue. Try to find the "Hot Rod" version if possible. It’s a killer amp.
http://www.soundstagenetwork.com/revequip/belles_150a_hotrod.htm
The 150A, (and 350A) REFERENCE amps had a version 1 and 2. The REFERENCE series amps had about twice the voltage output than the regular versions.
The 150 came in an "A" version and a HOT ROD version in addition to just the regular 150 original issue. Try to find the "Hot Rod" version if possible. It’s a killer amp.
http://www.soundstagenetwork.com/revequip/belles_150a_hotrod.htm
The 150A, (and 350A) REFERENCE amps had a version 1 and 2. The REFERENCE series amps had about twice the voltage output than the regular versions.