The Aleph 3 is 30 watts per channel, pure class A operation. The X150 is 150 watts per channel, class A operation up to 32 watts, then class AB at higher levels.
I believe these amps will sound largely the same. The greatest difference may be in the low bass, where the X150 should be more authoritative -- tighter and stronger, especially when the volume is turned up. You may also hear a difference in the midrange, where the Aleph 3 might sound slightly more liquid and tube-like. Whether to change amps should depend on what kind of music you like and your personal preferences on presentation.
I believe these amps will sound largely the same. The greatest difference may be in the low bass, where the X150 should be more authoritative -- tighter and stronger, especially when the volume is turned up. You may also hear a difference in the midrange, where the Aleph 3 might sound slightly more liquid and tube-like. Whether to change amps should depend on what kind of music you like and your personal preferences on presentation.