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If building a 300B SE, what would be more prefer for coupling between driver and output stage? Interstage transformer or capacitor coupled?

I've seen someone built an amp with 6922 DC coupled to 5687 and transformer coupled to 300B, but also have seen one with same tube complement but capacitor coupled. Pros and Cons between 2 different approach?
I heard transformer coupled is more efficient.

 

Andy Gove has written on the topic of interstage drive extensively. The URL below was accessible, but you can google on Andy Gove + interstage transformers to find more complete statements by him.

My experience is that the sonic variation (good to bad)in cap coupled SETs is smaller than for transformer coupled SETs. The best transformer coupled amps I have heard sound better than the best cap coupled ones, but a number I have heard do not sound as good as cap coupled SETs.

This suggests that as easy as some transformer coupled amps look (see the circuit design of the Audio note kits interstage monos at http://www.audionotekits.com/monob01.htm), they are not as easy to implement as cap coupled circuits, and a lot depends on the transformer quality ().

 

Personally, I will never build another RC coupled amplifier. Power triodes need a low impedance path to ground in order to prevent "blocking distortion" where electrons build up on the grid upsetting the bias and causing distortion. IT coupling does provide the necessary path for grid current but introduces other limitations and challenges. A very good quality transformer is required for the best sound.

I believe (and everyone has their own opinion) that direct coupling solves the issues with both RC and IT coupling. For more information search on "DRD amplifier" and "300B monkey amplifier"

 

I have built both. Although, I prefer IT coupling, RC coupling can sound great in a good design. The iron it takes to IT couple will run the BOM dollar amount way up.

How about cap coupling with grid choke loading?A good grid choke cost is a fraction of a good IT cost. There are some great sound PIO caps out there.
 

I drive ny 300Bs with Tango NC20F and the result is very very good! Better then a audio note silver coupling cap with grid choke, which is also very good. Anode choke with a top quality cap is also an option, but i think a good interstage like the NC20F is an investment for life. Good caps like silver foils also fail. Also know that cheaper transformers like the nc18 are not as good.

 
I've built several stacked supply, direct coupled amps and couldn't agree more.
Direct coupled is the way to go.

 

In my recent prototypes, I preferred capacitor coupling to an EI-cored, copper-wound interstage transformer. Capacitor coupling sounded higher resolution with more micro-details and micro-dynamics. The tables turn when you go to silver-wound, nickel cored ITs.

 

Both are easily bettered by direct coupling. Do a simple Loftin White two stage amp ala Shishido, Asano, with a good power supply..

It makes sense, a piece of (good) wire will mess less with the signal than a cap or trannie to drive.

Two stage amps will always be more transparent sounding than three stages, KISS rules !!!