Maybe it's just me, but I find that audiophilia is more of a winter-time hobby. Now that I can go fishing and to outdoor concerts, I find I spend a lot less time planted in front of the stereo. Of course, I'm also broke, due to quitting work to go back to school so that might have something to do with it.
One thing I've found that has really kept the upgrade demons at bay is DIY audio. I'm having a lot of fun building my first headphone amp. It's technical, rewarding, and most importantly, audio related, so I find it very satisfying, and also, quite inexpensive.
Of course, if someone handed me $20,000 right now, I know most of it would have to be sacrificed to the audio gods.
Regardless, it's nice to hear you're satisfied with your system. I like to say that I can't afford to be any more satisfied with mine. Happy listening!