Here’s a recording of Mendelssohn’s miraculous teenage Octet with a difference. Well, several differences, actually. The Eroica Quartet have gone back to the first draft of the work, revealing a fascinating stop along the route to the much-loved masterpiece we all know so well. The first two movements underwent the most thoroughgoing revision for the 1832 version (the one that’s usually performed) and it brings one up short on first hearing the young composer’s diversions in places such as the end of the opening movement’s exposition or much of its development. The Walpurgis-Scherzo and finale largely escaped the blue pencil except for the odd spit here or polish there (and 37 bars lost in the final movement).

Would the Octet have seemed such a miracle had it been published and become famous in this draft version? I don’t see why not: even in this form the work shows Mendelssohn’s preternatural ability to craft a sonata argument or a touching slow movement on the grand scale and, doing one’s best to hear this version with an “innocent ear”, there seems to be little or no redundancy or prolixity. The revision thus served mainly to tauten the structure, even if it meant losing some moments of striking aural imagination. The Eroicas and friends also adopt 19th-century approaches to style, in terms of bowing, portamento and vibrato. The result is a performance as exhilarating musically as it is absorbing musicologically.

One to rush out and buy then? There lies another difference. Resonus Classics is a new label whose recordings will only be issued as downloads. I listened to an MP3 at 320kbps, which sounded as good as anything else on my iPod and left little to be desired through stereo speakers; the recording is also available in a range of sample-rates up to 24-bit studio master. Prices range from around a fiver for the MP3, £6 for CD-quality FLAC and £12 for the studio master; you can also buy tracks individually. The download package includes a CD-size booklet pdf with excellent notes on the music and the performance. If you enjoy this Octet as much as I did, you can even click “like” on Facebook.