Originally Posted by Johnla
Ummm, yeah it sorta gets you a set of preouts, in a Rube Goldberg kind of way.
You understate old Rube's good work. ;-)
This is not nearly as arcane or inefficient as Rube's fertile imagination.
But it's not really the same thing as a actual preout from a AVR that actually has them or the output from a pre-pro/pre-amp.
Agreed, but it may be closer than you think.
All you are really doing is clamping down on the speaker outputs from the receivers own amps by running it through some resistors, to drop it's power output down to a level where it will not overload feeding a power amp.
It's not clamping, it is tapping down. It is as benign as a volume control.
It has the secondary effect of operating the receiver's own amps into a more linear mode of operation than driving speakers.
For example, most receiver power amps will stay out of class-AB operation and be running pure class A. Bass extension can also improve.
The receiver's power supply will usually truely be loafing.
The benefits over just a larger receiver are many. Far less heat, far lighter, and possibly smaller. Paves the way to system refinements involving equalizers, electronic crossovers, etc.
Probably not the best thing in the world as far as keeping a audio signal as clean and unmolested as possible, but I guess if all you are looking for is a very cheap way to add a bigger power amp to a AVR without a set of preouts, it's also probably about the lowest cost way to do it without buying a new AVR.
Exactly. But a good power amp is also just a big op amp. Sort of like the output stage of a good preamp on steroids.