'Yes' to both of those questions - we blend the two sounds AND it sounds different. When we say "I enjoyed the meal", the /d/ blends with the /ð/, producing a sound which is different from the /y/ + /ð/ combination of "I enjoy the meal". First, we articulate the /d/ by putting the tongue on the alveolar ridge (behind the teeth) to stop the airflow. Then, instead of releasing the stop, we glide straight into the /ð/, sliding the tongue forward to produce friction against the top teeth. This gives a d-like quality to the /ð/. A native English speaker can always perceive the difference between a /d/ + /ð/ combination and a 'plain' /ð/.

Hi Andrea, great question. In your example, the added ed doesn't add an extra syllable but it does add the d sound at the end of the word, so it sounds like: en-JOYD. The difference may sound subtle, but native speakers definitely notice the difference between enjoy and enjoyed. It's how we know what tense people are speaking in. Here's a good video on the topic: https://www.youtube.com/watch?v=9TPe_x80Pgs Hope that helps.

Both Olivia and Su.Ki. have given good answers. I just wanted to add, for clarification, that "the" does not begin with a "d" sound. Olivia's example, "I enjoyed dancing," uses a past-tense "d" followed by a word that begins with "d." But as Su.Ki.'s answer shows, the word "the" begins with a different sound. To native speakers, "d" and "th" do not sound the same. So "d+d" sounds different from just a single "d" sound, and "d+th" sounds different from "d," "th," and "d+d."