What is the difference between a solid state rectifier and a tube rectifier? How big is the difference? Thanks.
The difference is that a SS rectifier is more efficient than a tube rectifier. That means a small(~3watts) increase in wattage. Tube rectifiers cannot always keep up with the rest of the amp so they "sag," which gives the amp a springy feel- notes have a slightly compressed pick attack and then get louder. It's a cool effect, but whether you like it or not depends on your taste and style of music (it's great for blues but not so great for metal).
Another difference is that tube rectifiers have a capacitance limit, whereas diode rectifiers effectively do not. This allows SS-rectified amps to be designed with larger initial filter caps, which can increase bass, though there are many reasons why that's only a minor benefit.

It's a definite difference, but it's not huge. I have a switch to change from tube to SS rectifier on my amp- I only use the SS mode for squeaky clean jazz stuff. YRMV.
Last edited by Roc8995 at Mar 26, 2008,
Do note that though the rectifier affects the signal, it doesn't sit in the signal path and only affects it indirectly.
ESP LTD EC-256 and a Fender Deluxe VM