My stereo isn't doing it for me. Need advice

You have to have a reference for what sounds good to you before you can attempt to replicate it.

Have you heard a system or systems that sounds really good? What were they? What did it sound like? That would be your reference. Could be at a show, dealer or another person's home.

You can't hit the bullseye until you know where the target is.

other than that, on paper, the Class D amps are probably a better match to the Dynaudio speakers. I do not know of any Dynaudios that are tube amp friendly.

Other speakers would likely do better with teh PL tube amp.

I'd get a good amp/speeaker pairing in place with speakers that best fit your likes and your room specifically and then tweak from there.

So there are various ways you can practically tackle the problem but its hard to say what the best way is until the target sound you are shooting for can be better described.

BTW I own Dynaudios and run them off a very good quality BEl Canto Class D amp and this is a very good match to work with.

I have also heard KEF ls50s in my system. Like Dynaudios, these are also not tube amp friendly speakers. THey sounded good with my 500 w/ch Class D amps also in a smaller room but very thin off a different 180 w/ch SS amp (not Class D) in a larger room. These are good speakers but small so they can only provide full sound in a room that is not too big.

So all your speakers are a match on paper to teh Class D amp, and are not tube amp friendly. SO best PERFORMANCE with Dynaudios and teh KEFs will be achieved with a high power Class D or similar SS amp.

Applying a sub to offload the low end would work towards the end of using these speakers with the tube amp.

You have the best chance of getting the best sound fastest by optimizing the performance of teh gear that will be working together. Once performance is optimized, ie all gear is a technical match, tehn you are in a position to tweak teh sound to your tastes in various ways from there.

BTW I have heard of several cases where people were sold Primaluna tube gear by dealers with no consideration to what speakers would be used. In all cases the tube amp was changed to a more suitable SS or Class D amp specifically to get to where people wanted.

Or you could go with higher efficiency easier to drive speakers like Tekton or ZU or Klipsch for example to match to the tube amp better.

If tyou keep the PL tube pre-amp, make sure the input impedance of the Class D or SS amp you use with it is 40Kohm or higher in order to assure a good match between higher output impedance tube pre-amp and SS amplifier. IMpedance matching like this is another key for optimizing performance as a stepping stone to getting the best sound possible via tweaking from there.

I agree do not change anything until you have optimized what you have.

I have a 12X12 sunroom with cathedral ceilings that is my acoustically challenged room. My gear sounds fantastic in my other rooms larger and similar size, but that one was always a tough challenge acoustically. Its small but very lively with windows on 3 sides and reflective tile floors over a vibration prone modern suspended plywood floor.

I finally solved it and have it sounding spot on with small monitors positioned just a few inches off the floor with slight upward tilt using short and inexpensive Isoacoustic brand stands available on Amazon.

There was always too much or too little bass in this room not matter what I tried. Floorstanders, monitors on stands at ear level mostly.

The Isoacoustic stands were the key. They enable bass reinforcment from the floor from teh smaller Triangle Titus monitors but keep it clean by isolating the speakers from interacting with teh floor rather than coupling to it, as is usually the case with most floorstanders or monitors on stands.

Now that room is one of my best with perfect full articulate bass and all the rest in spades.

The key was getting the bass under control by isolating teh speakers from interacting with the floor using teh Isoacoustic stands.

OPs case may be similar or different, don't know. But thought there enough similarity to throw this seldom discussed and relatively inexpensive tweak option out there.

SOund Anchor are nice stands.

If those are sounding good 24" off the ground, the Isoacoustics I mentioned might be worth a try. These are less expensive pro stands and very effective but are short stands designed to be used with pro studio monitors. Can be used on floor, desk wherever needed. Three sizes available. One of those would likely fit the smaller Dynaudios or ls50s.

Which speaker are you talking about now that you are hearing better results with different stands and nearfield? The Dynaudios, KEFs or both?

http://www.amazon.com/IsoAcoustics-1004209-ISO-L8R155-Medium-Pair/dp/B008GOP79G/ref=sr_1_1?ie=UTF8&qid=1432133841&sr=8-1&keywords=isoacoustics

If you need a pair of inexpensive but effective isolating speaker stands for smaller speakers in a small room, you probably cannot go wrong with these. They were one of the most unique and effective tweaks ever for me in my wife's small and acoustically challenged 12X12 sunroom.