I read 2 or 3 books in this series in the UK, sometime between 1985 and 2000, I can't recall if paperback or anything about the covers.
I don't remember too much about them, he's a young magic user in a modern urban environment, I think in the US. He wears a suit of like mithril chain mail under his normal street clothes.
He's had several bad injuries when fighting demonic monsters and, as a consequence, he has this massive high tech bed. He bought it used, it was designed by some eccentric and it's got lots of stuff like built in massage pads, retractable TV screen (an amazing idea back then), stereo music etc.
I think he lives with his aunt or granny and they're often horrified at his injuries, but they're not aware of what he does for a living.
That's all I got