Monoblocks, tube or otherwise, really have only two advantages over a stereo amp
1. You can put the amplifier right next to the speaker, eliminating the cost and reputed sonic degradation due to speaker wires.
2. A high powered stereo amp, particularly a tube amp with two massive output transformers, can be too heavy to handle.
If the stereo amp is well designed, the shared power supply and circuit proximity of the two channels is not a problem.
1. You can put the amplifier right next to the speaker, eliminating the cost and reputed sonic degradation due to speaker wires.
2. A high powered stereo amp, particularly a tube amp with two massive output transformers, can be too heavy to handle.
If the stereo amp is well designed, the shared power supply and circuit proximity of the two channels is not a problem.