Up grading power amp... Mono blocks or stereo amp?

The primary argument for monoblocks other than shorter speaker cables (which by itself is a pretty important thing) is that there are no shared power supplies. An amplifier that has separate internal power supplies will be described as 'dual mono', but most stereo power amps do have shared supplies. In most stereo amplifiers, the incentive is price, as the chassis is often the most expensive part, followed by the power transformers.

Conversely, monoblocks are usually built to a higher standard as cost plays less of a role.

Overall these are generalizations, but good to keep in mind when looking at a specific product. They often are helpful in guiding one to an audition, but the audition is really the bottom line.

Atmasphere...Another important advantage of monoblocks, at least for high power units, is that they are not too heavy to pick up! That, and the short speaker wires is why I have monoblocks.

I think that the shared power supply thing is a bum rap, at least for the amps I have owned. It is usually only the transformer which is shared...each channel gets its own capacitors which will continue to run the amp for several seconds after its ac power is removed. One trick to help amps with so-so power supplies is to run one channel inverted, so as to even out the draw on plus and minus rail voltages. Some amps (the old dynaco ST120 is one) are spec'd for power with one channel inverted.

And thank God the MA-2s are monoblocks:)

Eldartford, in a power supply with plenty of capacitance the caps are only charging at the peak of the AC input from the wall. At this point the rectifiers turn on and off (commutate) only at the peaks. So you have a spike that is riding on the top of the AC waveform from the wall.

Double the current and the spike is bigger- more noise will be present in the power transformer core. In addition, power drawn from one channel can lower the output voltage of the power transformer secondaries due to the internal DC resistance. This can affect the other channel (slightly). If *both* channels are drawing a lot of current, the voltage sags more. Its not a bum rap, its just what is.

A designer of a stereo amp has to consider these things. Its not really a problem in a monoblock.