Does anyone care to ask an amplifier designer a technical question? My door is open.

I've always hoped Roger would take the time to join the forum here.  My RM-10 Mk II that I bought new from him in 2011 is my last amp.  He personally burned it in a few days before shipping so it would be trouble-free and it has remained rock solid.  People like Roger, Ralph and Almarg make a tremendous contribution thank you all!

Roger— thank you for sharing your expertise in this thread.

I would like to know your opinion of ideal amplifier type (and your rationale) for the following loudspeakers:  Vandersteen 5A/5A Carbon.  As you know, this product is relatively inefficient but uses active crossovers with bass amplification built in.

If you could specify examples by brand, that would be ideal, but I’m also interested in general advice re: power requirements, etc.

Thanks again!

Thoughts on the Stereophile measurements of this Luxman solid state amp?

https://www.stereophile.com/content/luxman-l-509x-integrated-amplifier-measurements

@unreceivedogma

Why would triode sound better than pentode?

Why woukd my Altec Lansing 604Cs be better for my Julius Futterman OTL3s At 16 ohms rather than 8 ohms?

And, with regard to the great interconnect debate: do you know of any testing done that approaches that of scientific blind testing that shows that any given wire, if made out of a certain material, and wound in a certain way, and shielded in a certain way, will cause electrons to move in one manner as opposed to another that can be explained as doing so and that because of that movement can be explained as yielding sonic performance that is measurably and quantifiably superior, or even just different?

Good stuff, lets go.  Triodes have inherently low output impedance and one can make a nice amp with little or no feedback and still get good performance in the areas that matter: distortion, output regulation being the most dear.

Pentodes have high output impedance and something must be done to get this down by using feedback. Pentodes became popular because they produce more power per watt of tube. For instance a single 6L6 can produce 6-8 watts single ended but 100 watts per pair push pull, in pentode. Perhaps only 20 in PP triode.

The problem with triodes is saturation voltage pure and simple.

All OTL amps like high impedance because they have lots of voltage but limited current. Since current is the limit use the forumla

Power = current squared x impedance. The amplifier max current is the same for both speakers but 16 ohms gives you twice the power of 8. 

Some cables intentionally modify the frequency response and act as filters. MIT is famous for that. Some cable makers, like those liquid metal guys, have made up a whole story of fake science to sell their wares. Some makers freeze their cables, treat them with RF from a  Tesla Coil, yada, yada, yada.  I think you can tell I dont think much or cable makers, especially the really expensive ones. 

The whole idea of tuning a system with cables seems rather weak to me. Harry Pearson was big on cables but he was an idiot. Since I brought him up, my favorite quote about HP, which he said to me in person as he leaned over his Corvette at Sea Cliff is... "Audio is a Drug and I'm the Audio Pusher".. I think that pretty well describes Harry.

RM - what starter book on basic electronics / circuit s would you recommend ?

This one, price varies widely. Its a good text. I got one for $5.

https://www.amazon.com/Analog-Electronics-Devices-Circuits-Techniques/dp/0314045538