They're both very good, and you have to be pretty golden eared for the difference to be meaningful to you. The ML39 gives a good, honest presentation with a flat frequency response, decent dynamics, and good detail. In comparison, the SCD1 sounds a little rolled off on the high end, which actually makes it sound smoother and richer, a la tubey, but not in a very pronounced way. For example, cymbal sounds have a "shhhhh" character on the SCD1 versus a "ssssss" character on the ML39. It's a small difference, and I hope I'm not just hearing different hands on the mastering boards. The SCD1 has similar dynamics but seems to enjoy better detail retrieval. Quiet sounds have more shape, better definition, a beginning-middle-and-end to them, versus a small splash of mainly middle sound on the ML39. It becomes a question of your taste. By the way, I recently upgraded my ML39 to the ML390s. With the upgrade, the unit sounds much more dynamic, punchier, and somewhat brighter. It's clearly better. I prefer the ML390s over the SCD1 because I like bigger dynamics more than better delicacy.
