Though I have not studied the different recordings of this music, and therefore cannot comment on the relative merits of this set, there is no doubt that here the musical values of these most important performances are extremely well conveyed. This is especially true of certain qualities which make this music uniquely powerful. I refer to the stereoscopic voicing of Armstrong's solos, which becomes characteristic of his playing towards the end of 1927, and continues through to 1931 (from track 18 of disc 2 to the end of disc 4). An explanation for this musical phenomenon lies in the interplay between syncopation and rubato, and occurs most clearly in pieces in which the former creates a lively basis for the rhythm of the music. The consequence of this interplay, along with dynamic contrast and other variations such as those of sound and pitch, is to make the cornet or trumpet stand out in relief against both the accompanying rhythm and the melody. For, while departing from it, the solo evokes the original line both in the harmony and in its own melodic shape. Most significantly, it retains the pattern of syncopated rhythm that is distinctive to the melody and also provides a basis for the interplay with rubato. Though this stereoscopic voicing is characteristic of at least half of the pieces in this set, it is sustained with great cogency and depth of expression on the following: Once In A While, Savoy Blues, No (No, Papa, No), Basin Street Blues, No-One Else But You, Heah Me Talkin' to Ya and Tight Like This. In my view any one of these is worth the price of the whole set.