Things to whine about: It lacks the "Rec-It"-Feature that can be used in conjunction with Control-A1-equipped CD-players to record the track you are listening to with a single button push. No idea why they dropped it - perhaps to give their CD-MD-combos a chance. And: Even though it is equipped with pitch control, there is no way to increase speed - no more "Mickey-Mousing". I wonder what's the use for this feature, which is described as the possibility of adjusting playback to your instrument. What I miss very much: The resume mode of the MDS-JA50ES and its facility to switch the display off.
Enough complaints! The looks: Slight changes in the layout: the AMS-knob has moved below the rec-level-knob. The switches for input and rec-mode have been replaced by two buttons, forcing the rewind/forward-buttons to move under the play, pause, and stop buttons. All push buttons for advanced functions (filter, SF edit, display etc.) are a bit smaller and look less professional than before. The disc loading mechanism features a new cover which moves inwards when inserting a disc, and outwards when ejecting it. Total time and track time are now displayed without "m" and "s" behind the digits.
The most important feature introduced with the 940/640-units is the Scale Factor Edit-facility. It allows you to adjust the level of whole a track in steps of 2dB or fade in/out a track within 1 to 20sec. Scale Factor Editing takes some time to execute: Fading in or out will take about the amount of time you've chosen for the fade. That's o.k. and works fine. But adjusting the whole track's level requires about the same amount of time as the playing time of the track. Imagine a whole MD recorded at a low level, raising its level with SF edit will take you up to 80 minutes.
MDLP-modes are a tribute to MP3 and CD-R. In particular the LP4-mode with joint-stereo compression and a maximum record/play time of 320 minutes should not be taken too seriously in terms of sound quality. And since those recordings aren't compatible with your old equipment and SF Edit won't work with those tracks I don't like this feature very much. As my 920 isn't there anymore for A-B-comparison, I entrust the guys at the HiFi-magazines with evaluating the sound.
Test-Mode is accessible (push AMS-knob while plugging in), Service-Mode too (AMS+stop), with those odometers. TOC-cloning should be possible. Quick-access-by-time-trick works, too: while playing a track, push the AMS-button as if dividing the track, push the forward/rewind button until minutes or seconds are flashing in the display, then turn the AMS-button for the time point you want to access and cancel with the menu-button: There you are at e.g. 3:43 and the TOC isn't touched.
New, useful features (SF Edit) paired with less useful ones (MDLP), reduced by some features I got used to (adjustable playback speed, Rec-It): The MDS-JB940 causes me some doubt as to whether I really bought the best replacement for my 920. But it would have been hard for any other MD-deck to compete with the 940 if it really had EVERYTHING. Who would buy an MDS-JA555 (sound, pitch) or MXD-D3 (rec-it)?