Can I get my Prima Luna to sound more like a SET/300B?

In short, no you cannot, but you can tailor it in that direction. Something about the circuitry and transformers in the amp prohibit it from getting that smooth, and it’s hard to even get conventional tube sound out of your amp as it is very linear aka solid state sounding as a tube amp. I’ve owned the amp multiple times over the course of ten years and have plenty of experience with it. 

That said, a few things to potentially try before you invest serious money into a new amp. 

• Get the Psvane EL34PH for output tubes. They are the most 300B-like EL34 I’ve ever tried. Just really wonderful… golden, rich and harmonic, a bit rounded and refined on the frequency extremes, especially compared to the others you listed. 
• Brimar CV4003 on the first two (center) tubes. These are also a bit more refined and softer sounding than the hashy stock tubes.
• Quality power (cables and conditioners) can also do a great job of enabling an amp  to perform its best.

Why would you want to do that? Ralph Karsten of Atmosphere has posted here on another thread about why a well-designed PP tube amp is inherently superior to SET amps. Single end amps are distortion-generating devices. Past the first 25% of wattage distortion rises rapidly to 10% or more. That can hardly be called "high fidelity!" The 300B tube has a usable 2 watts available! At 8 watts it's distortion is 10% and rising! Forget SET's! Stick to PP 6L6/5881/EL34/6550/KT88 types.

The OP should ditch the Gold Lion KT77's and buy a set of NOS RCA 6L6 Black Plates. I have a quad set to use in my Heath W5 monos.

Rather than hack your power amps (which will destroy their resale value), time to start shopping around for different power amps. Your speakers are pretty efficient, so 15 to 20 watts should be plenty. There are some push-pull 300B amps out there (Don Sachs and I make some, but out of your price range) that are very good. There are some pretty decent SET 300B amps in your price range as well, but they are quite variable in sound, depending on design details like driver design, power supply isolation, and more subtle details like point-to-point wiring vs circuit boards.

I should mention designers of Class D amps sometimes (not always) use an analog front end to deliberately "tune" the sound of the Class D power section. As a result, there is no one Class D sound ... each Class D brand needs to be auditioned to determine their house sound, which you may or may not like.

So ... you can choose PP 300B, SET 300B, or a "tuned" Class D amp. I am a little hesitant to recommend any push-pull pentode amp, because it’s very difficult to get the distinctive 300B sound with that topology and tube choice. There are definite limits to what you can do with cap swaps and power supply tuning.

P.S. Single-ended pentode amps live in a world of their own, quite separate from PP 300B, SET 300B, or PP pentode.

Hello all,

I will be spending some time combing over all the information on 300B, SET amps, and the like, and this will take some time! I am looking forward to the potential here… 

But yes I read through that thread and I do not disregard the Prima Luna’s potential. 

So, considering that my Gold Lion KT77’s are biting the dust, I would like to consider the options you all mentioned as well as ask you all if you have a sense of a few more I have come across as contemporary options:

-Psvane EL34PH: These seem possible as an option, though perhaps I seek something with a bit more flair…

-NOS RCA 6L6 Black Plates: These seem very pricey and difficult to source in quantities of 8, as my Prima Luna require…

-TAD Red Base EL34’s: How are these? I have heard they may surpass a mythical NOS tube… (forget which, from a Satori review of the Psvane)

-Ray Tubes: These seem to get written up well, though pricey…. Any personal experience with Ray tubes? 

-Sophia Electric: Anyone have experience with these? Supposedly great with acoustic…. 

THANK YOU much for your impressions… 

r.

SED EL34 from the 90's are best EL34 I've heard. I've had a number of pp and SET amps, closest pp to SET sound I've heard is my newly purchased PP monoblocks based on Bendix 6094 tube, this has 12wpc. I also used to run Prima Luna Dialogue, mods will only take you so far, but some nice EL34 and something like Jupiter copper foil coupling caps will help that amp.

@jasonbourne71 + 1 - good suggestions; many other NOS upgrade KT77s would sound better than Gold Lions as well. Tube upgrades can be very well worth it.  

1:NO YOU CAN NOT...
2:With your speakers why are you messing around with an amp other than the amps you know give you the sound you want?

@whyrichard Hello I went down a trail similar to yours, and so glad I left it all behind, what a relief. 
   I got involved with lots of tubes stuff my last big mistake was the PL EVO 400 pre, PL EVO 400 amp and just to put the big mistake cherry on top free falling down the rabbit hole the PL Dac. For a solid year I tried different tubes and spent a lot of money for nothing. When the amp blew a fuse and a EL34 stock tube quit working that was it for me, bought all new stock tubes and sold all the PL stuff to one great local guy. 
  Now what, no amp or preamp done with tubes I spent a lot of time with emails to Nelson Pass a great guy, (long story short get rid of  the tube stuff), I ended up with the Pass Labs preamp, Pass Labs XA-25 amp waiting for the First Watt Sit-4 to began production..the Sit-4 arrived 6 months later, it’s glorious, not more tube stuff running through my brain…do yourself a favor get solid state that sounds good to your ears, otherwise you will always be falling into that tube rabbit hole…I am now in music nirvana, Pass preamp, First Watt Sit-4, Volti Audio Lucera…