can someone answer me this.....

i have done some extensive research and talked to quite a few people who own or have had this preamp.  I recently came into a conrad Johnson et 3 se, nt much clarity,the bass is muddy and the presentation is dark, ive read where some claim the system is to bright.  ive also read where its good to get a specific type of tube.  I don't want to do that just yet because im trying to learn the units characteristic.  I wonder if its not quite broken in yet.  maybe the impedance thing that Im just learning.  steve mccormck suggested that I try some after market power cord, that I ordered.  
assoc. equipment
McCormack dna 500
oppo 203
alon IV's
acoustic zen interconnects
I make my own speaker cables …..
no wires are touching, none are on the carpet or floor.....
A combination of bad tubes and a source component (Oppo 203). Replace the bad tubes and upgrade from the Oppo 203. 
I think the Oppo 203 is your weakest link in the chain. Front end source component(s) are the most important element in hifi chain. 

almarg speak English, my head started hurting, followed by flashbacks of science
The point I was making in my previous post was simply that while the impedance situation in the connection between the preamp and the power amp is not ideal, and does not conform to the recommendation stated in the manual for the preamp, I’m pretty certain that it is not what is causing the symptoms you have described. And I expressed agreement with Ralph (Atmasphere) that a tube is the most probable culprit.

The reason I went into further detail in that post is that you had referred in your initial post to "the impedance thing that Im just learning."

almarg, don’t know a thing about the imped factor. and do you still have that 17ls. or what preamp goes best with the dna 500....

It was another poster who referred to the 17ls, not me.

-- Al

I have your amp and pre-amp.  Before getting the ET3SE, I contacted Steve McCormack and he said there should be no issues pairing the two.  I use  an Amperex 6992 from Andy's Vintage Tubes and have been very happy with the result.  As mentioned by others, be sure to account for phase inversion by reversing the positive/negative terminals either at the speaker or amp ends. The sound you describe could be a result of forgetting to do so.
If it's new with little hours of play time my thought is break in. My CJ took hundreds of hours but once those caps are broken in the sound was wonderful. Roll tubes once it's broken in.
If your pre takes a 6DJ8 / 6922 tube(s) you have limited alternatives.  The used tube market for vintage NOS Siemens 6922's, especially Cca and grey plates is like looking for unobtainium.  I've been using them for about 15 years, after testing maybe a dozen or more different brands and time periods and simply have no more nor are there any real ones out there.  What I have found which seems to be as good, or nearly as good as a Siemens and Halske Grey Plate early 60's Cca is the 75 vintage have no connection to this person other than I have purchased tubes from her 6 times.  Everything arrived very securely packed and was exactly as advertised and they perform exactly as they should.  It used to be $99 a pair now it's $219.  Siemens and Halske Cca grey plates used to be $40 a tube then they were $400 a pair, now there are no real ones.