in response to your question, I didn't put a lot of thought into the details of the difference at the time because the improvement was so immediately obvious, and I couldn't go back to the stock unit to A/B. But it did sound more 3 dimensional, and perhaps I also just like the sound of tubes, when they are not too colored. If you are one of the people who finds CDs to lack certain desireable qualities that LPs have, you will know what I mean in that those CDs sounded much closer to the vinyl, with the vinyl only marginally better.
Also, unlike a lot of people, I wasn't so exited about the sound of the stock unit, though it was very good for the price.
I was content with the stock tubes, but for the first time I am trying some different tubes in the unit , and just discovered Modwright now has an upgraded umbilical cord available for their units, which should arrive shortly.
wifes here, gotta log off!!!