I'm running a Marantz 6170 DD turntable with a Grado Black cartridge through a JVC receiver and a set of Marantz floor speakers. I think it's a pretty decent budget setup (the $50 cartridge was my biggest investment - everything else was free), but am looking for ways to improve it. The sound is "warm" and has a good kick, but lacks detail.

My question is whether it's possible to improve this setup significantly while still on a tight budget. I wouldn't be able to spend more than, say $150 on an upgrade, and even that would be pushing it. For that money, I'd be looking for something that a) offers a noticeable improvement from the get go and b) would not need to be immediately replaced when my budget grows.

Is this possible? If so, where should I be investing this money? My own research has led me to believe the weakest links in my system are the cartridge and the JVC receiver. Can $150 buy me a decent phono stage or a cartridge that is noticeably better than a Grado Black? Should I be looking somewhere completely different?

Don't be afraid to tell me that my budget is too small to do anything. The last thing I want is to spend $150, a significant sum for me, and get nothing out of it. If I have to wait a year until I can spend $300 or more, I will.

Thanks for any advice!