Hi Phil, don't know if you've seen this one, but I use a programme called iReal, which provides rhythmic accompaniment. You can select from quite a wide range of available songs, or choose a rhythm and create your own chord chart, if what you're playing isn't already there. You can change the tempo, transpose into different keys and choose from a small selection of instruments. The volume of each instrument is also individually adjustable.
And it isn't overly complicated!!
The most popular music practice app on earth just got even better. Master your art by practicing with a realistic band that can accompany you in any song or style, whether you’re writing your own or at a jam session with the band.
www.irealpro.com
If memory serves, cost about $20US.
AndyM