PrimaLuna Evo 200 underwhelming

As strange as this sounds, I had a similar experience with a PL Dialogue Premium.
After 150 hours it still sounded disappointing (mostly veiled). Preamp was a Don Sachs...so no problem there.

My (nos) Carver TFM-35 was put it back in the chain. It was easily smoother, more detailed with upper end sparkle. Gave me a lot more respect for this amp. 
Decided to give PL one more chance and traded up (luckily at no cost because it's Upscale Audio) to an Evo 400. It sounded great from the first note and just got better from there. Not an ounce of hyperbole to say it was an ocean of difference from the Dialogue series. 

My take: There are a lot of people who swoon over their Dialogue series, so maybe some doped ones get through QC? Otherwise I can't explain it.

Also, I have messed up the phases on the speaker wires on the PL. As mentioned, very easy to mess this up on PL.

My Salk speakers are 88db/6 ohm and dip just below 4ohms. Sounded great using 4 ohm taps for a year. Just changed to 8ohm taps and I now get a slightly better presentation in upper midrange and highs... still have good bass slam.

I use Tung Sol 7581A. A little upgrade from stock EL34. More upper end sparkle, same midrange smoothness...a shade more deep bass. Less power though.

A word about Primaluna: if you're looking for ultimate in detail...look elsewhere. These are fun, smooth and romantic sounding amps with good bass slam. 

If you feel it lacks dynamics swapping to KT88's will help open things up. I much preferred KT88's over el34's and my speakers are also 86db. I'd try those before KT120's or 150's to stay within the comfort zone of the rest of the circuit. You also mentioned that it sounds muffled which can be a characteristic of the preamp tubes, in particular the gain tubes. I'd start by swapping the gain and driver tubes if you don't have any extra 12Au7's on hand, but it's worth experimenting there as well.  The preamp stage has a huge impact on sound quality, particular transparency, so don't overlook the small tubes.       

Also:
Tech at Upscale audio said I needed a full 200 hours for the Dialogue Premium to break in.
I honestly couldn't see it covering that much ground in 50 hours but maybe I was being hasty. Anyway, glad I traded up.

I demoed the Prima Luna Evo 300 against four other tube integrated amps; see https://forum.audiogon.com/discussions/integrated-tube-amp-demo-follow-up. In comparison, I found the Evo 300 to be somewhat veiled, or "muffled", in its sound just as you have. 

BTW, I have now moved on to a Pass Labs XA 30.8, with Conrad Johnson preamp, which is another giant step up in sound quality.

Thanks again for your comments and suggestions. There is a lot to take on board, so please forgive me for not replying to each response, I am not sure how to do that but I appreciated every one of them. There seems a lot more to owning a tube amplifier than I ever could have imagined. Thanks.