First, a bit of background: Some years ago, I arranged a number of beginning/intermediate-level duets of famous classical themes, for clarinet and alto sax. After trying the pieces with students, I self-published them, adding key-compatible versions for flute, trumpet, and tenor sax, and distributed them to local music stores. One of the store owners suggested that I send them to Mel Bay Publications, and the company decided to publish them, providing a far wider distribution.
Bill Bay suggested that I add a violin version, as well as piano accompaniments. That was a very good call; the violin version has consistently been the best seller. My mother, Jannette Spitzer, and my sister, Laura Spitzer - both fine pianists and teachers - created piano accompaniments, which were packaged with the instrumental duets. The piano parts are pretty easy, too.
A few years later, I added versions for viola and cello. The books for band instruments are all mutually key-compatible and in friendly keys for those instruments; the violin, viola, and cello books are mutually compatible, but in string-friendly keys.
The books can be used as like-instrument duet, mix-and-match duet, mixed ensemble in two parts, solo with piano accompaniment, or duet with piano accompaniment. Altogether, over the years, the series has sold over 40,000 copies.
A couple of years ago, Laura recorded all of the piano accompaniments, so that they could be posted online as "backing tracks." It took a while for Mel Bay to revise the print version and post the tracks online, but the new books and online tracks are now available. Each accompaniment comes in a "practice" tempo (slower), and a "performance" tempo (more challenging).
I have used the clarinet and sax books with a great many students over the years. I generally use them in their original duet form. I think they make a good curriculum for students who are just past the "first band book" stage.
If you are a teacher, and would like to pick up a copy and/or have students do so, I strongly suggest that you buy it directly from the publisher. Don't get it used, or from Amazon. The instrumental duets are printed on an insert, inside the printed piano accompaniment. Warehouse employees don't understand this, and sometimes have shipped the book without the duet insert.
The books are also available from Mel Bay as eBooks. If you (like me) are increasingly using an iPad for reading music, I recommend a 13-inch iPad Pro. On smaller tablets, musical notes may appear too small. Amazon offers a Kindle version of the Easy Classics books, but most Kindles are just too small to be useful this way.
If you are in the market for a 13-inch iPad Pro, here are some options, new and "renewed." (Full disclosure: If you order anything from Amazon via links on this site, I receive a commission.)
Anyway, I'm quite happy that the recorded accompaniments are finally available. Perhaps a few readers will find these books useful in teaching. Thanks for indulging my self-promotion!