Newbie question-- where to throw my frogskins next?


Hey folks, my first post--

So my new year resolution was to get into vinyl and these past 11 months I've been on an very enjoyable, and thanks to craigslist fairly affordable, audiophile neophyte journey.  I really barely know what I'm doing, but think I've lucked onto a pretty sweet vinyl setup;

AudioTechnica 120 turntable (with their standard cart)
Marantz sr7007 (using pre-outs for front speakers, but built in for surround speakers)
Moscode 300 ($150 craigslist score!)
Klipsch Forte I (replaced crossovers and tweeter diaphragms) 

So my question is, if I wanted to throw about $1000 at this system, where would I actually hear the biggest difference?  Better turntable?  Tube preamp?  Save my money as the difference would be negligible?  

I'd love to find a deal on a Mcintosh preamp, but the truth is I use the system for home theater and gaming and appreciate all the HDMI switching and surround sound the Marantz is giving me.  But I am also listening to vinyl every day now...  :-)

Thanks in advance for any advice!
128x128argonsteele
By the way we all started just like you. Nothing to be ashamed off. You can pick up a very nice Tube preamp on audiogon within your range.
Yes my turntable is the USB model with the At-95 cart and I am using the phono stage in the Marantz.   Yesterday I spent and hour reading about removing the phono stage from the turntable, but I think I'll hold off on that adventure for now.  More than anything this thread is confirming that I was at least already pointed in the right direction.  I think I'll continue to pursue all three paths at the same time; some small affordable up-grades now, like cart and maybe phono preamp, while looking for the right deals on a better turntable and tube pre-amp.  Both those larger ticket items are intimidating because there are so many more obscure choices out there at the mid to high end.  Guess it's more hours on the internet for me.  (I spend some time learning about the Linn axis this morning, which I'd never heard of, but I'm a little afraid of that eBay one as it seems to need a new power supply already).  Deep in my heart I want a Mcintosh tube pre.  

One follow up question.  Do others agree that the Moon phono preamp suggested by 2channel8 is a good choice?  That seems like a sweet price I could take the plunge on today, but I also know there are many options in that arena.   :-)
Ah, my poor friend. You are obviously one of us helpless addicts now. What a sweet addiction. Don't spend so much time on the net that you neglect the listening.  :^)
:-)  OK, I pulled some triggers.  Ordered the moon phono amp after reading a few reviews, the AT 120 EB cart, and a cork mat for my turntable.  That's my budget for this week.  I'll continue to troll craigslist for the bigger items.  Thanks everyone!  
Just Curious what tubes are in the Moscode.  There should be 4, total??? They may be good ones ,or if it was tube raped (or they were dead), some new cheap stuff.  New tubes are good because it will work correctly, not be noisy etc.  Old is good,- if tubes are working and also in good condition.  Older tubes sound better than new production tubes. in many instances and are more valuable.  Contact me and I will tell you what you got- if you want.  No I will not buy etc, just advise.
The Phono Preamp choices are numerous.  I don't know what you want to spend, (About $400) but the Graham Slee 2SE is very very good, I love mine. Did anyone tell you this can be an expensive hobby.