Hand me down audio equip- upgrade advice

I agree with room treatment. I also agree that you have to spend more for a real speaker upgrade. I used to own the KEF 103/3 until I got the bigger and better (although older) 105 which I also restored. My 103/3 had the LF drivers refoamed and the donuts replaced. Fresh ferrofluid for tweeters. Crossover was recapped with Alcap from Falcon Acoustics. The KUBE also got new electrolytics. The 103/3 when properly restored are great speakers. 

@rillerr,   I wasn’t familiar with some of that equipment and went to look it up. That was a very nice gesture for him to give you equipment of that quality and value.  I wish I knew people like that — any boss, friend or acquaintance I have had would gift me an Emerson radio with a cracked case and broken antenna!

Nice gift from "da boss"!  I would suspect he or she is a valuable resource as they owned the equipment and upgraded the whole system.  Maybe you can follow that same road to a lesser degree. Get the room straightened out, that will pay you back with any system you acquire.
Good luck, go slow.

Lots of good advice above.  $1500 doesn't get you in the game these days unless you get lucky, or can fine another mystery benefactor!  I remember the 103/3 w/KUBE without a lot of fondness, so the upside is large if you are willing to re-foam another used pair of classics...find a good pair of Theils, Snells, or a/d/s L1290s if you can, or SF Grand Pianos.  Also, if you are handy with woodworking tools, consider a pair of Dayton Audio Solstice from Parts Express...all Morel drivers.

Thank you all for your comments and suggestions! To answer @three_easy_payments and some others- I don't have any acoustic treatments currently- I'm actually planning on moving in the not too distant future... so much more effort will be put into the room after that happens. 

I didn't know a ton about higher end audio equipment until after I received this equipment as a gift, and after doing a lot of research- I'm very blessed and thankful indeed! 

@barts I have been working with him on plans for an upgrade, but he is currently very far out of my league on everything... He has given me some solid tips and advice though. 

@audite84 and @crustycoot Did you personally refurbish your 103/3's? or did you have someone else do the work? I refoamed the woofers in both speakers, but haven't touched the ferrofluid in the tweeters yet. I've been debating whether or not to do it myself or have a shop do it. I know from what I've read that the tweeters are probably less than ideal as they sit- but I have to say I'm still not convinced they sound bad by any means. I've also had my eye out for older Theils and SF varieties, and will continue to look. I'd love finding an older pair that's not too beat up that I could refurbish.

@guy-incognito I've been having the same inclinations you mentioned, I'll probably just continue to hold out until I feel comfortable spending $5-8k and in the meantime keep an eye out for deals of older proven speakers that I might be able to bring back to life.