I've had Bose speakers for several years (Acoustimass III I think). Two little satellite tweeters and one subwoofery box. Purchased a pair of Grado headphones a few years ago and discovered how bad the Boses are. My eyes opened, I've been caring more and more about sound and liking these speakers less and less. Seem especially weak the more complex the music is--large chorus and orchestra pieces. Mud. But I've made my bed and have to lie in it until I can accumulate the money I need to climb out.
Any relatively easy and CHEAP ways to make them sound better?
Listen mostly to classical and jazz. No home theater, etc.
There are ways to improve 'normal' sized speakers. Ensuring that the drive units are properly sealed and sticking bitumen sheets to the inside walls of the enclosure to deaden vibration are cheap and easy improvements.
However, I don't think you be able to do much with the Bose system.
How about selling them (I imagine that Bose sell easily 2nd hand) and getting some used Tannoy M2s or similar to be going on with?