Comparable to Magenta? Magenta is base on the TensorFlow machine learning framework. Mxnet and caffe are two other ML frameworks. Caffe is single threaded. Mxnet is highly parallelizable and can outperform TensorFlow. All three have implementations of style transfer, which has been the most common artistic demo of ML (this is what's going on when you use a Prisma filter on a photo, for example).
Only the Google Magenta team has taken so much time to engage artists and musicians in exploring the humanities side of ML. I feel this is a real missed opportunity for the Amazon folks who are eager to see more mxnet adoption and I've told them so. Kind of hard to bestow humanities appreciation in folks who don't naturally have it, unfortunately.
The demos here do a great job of demonstrating the potential. Be sure to check out the AI Duet in particular.