Ah, I meant to say older hardware.  Such as a presonus firepod which was prefectly acceptable.  when I upgraded to a TC Konnekt I could hear a difference, mostly due to preamps.  Not soul changing, but definately cleaner, deeper and more 3 D.  Funny, some older, jazzy stuff actually sounded more analog on the Presonus than the TC.  I'm sure the RME is a bit better than the Roland, but I've never heard them side by side so I wouldn't swear (tho I know all the words!).  It is too easy to believe "that is the bomb" when there is only a red-hair difference between units.  the actual convertor chips used all come from a couple of companies - the design difference comes in clocking and the analog components around the digital.  And you pay for incremental increases in quality.  A hundred dollar interface, in the big scheme of things, sounds fractionally less good than a $2000 interface - certainly not 5% as good.  There might be a 5% difference between them, which only becomes apparant over a nice system in a good room.  And trained ears that know what to listen for.  Most end users (the audience) won't hear such, or at most on a subimial level.  The idea is to get the replication of the music out of the way of the audience.  Just like writing (or any craft) you don't want others to wonder what you are saying or even how you are saying it - it is the message.
 
As Jonesy says, you have to think of the room and speakers as a system.  A small room doesn't work well w/ a big speaker system.  A small woofer can't reproduce the bass frequencies (cleanly) for hip hop.  An empty room will have a slap back echo, timed by how big the room is (if you ever have been in an empty house or apt or cleared out a room for painting, try clapping).  It will smear your transits and thicken up sustanied sounds which won't be the same in the room others are listening to your mix.  The idea of room treatment is to attenuate the echo of an empty room.  Every room has resonant frequencies where the sound bounces off walls and reinforces that frequency, as well as where the bounces cancel out each other and makes nulls (or a lack of sound that is present in the original).  And these all shift as you move about the room.  So you want a single position where most of the frequencies are flat where you can listen from.  Even putting a couch in a room will absorb a lot of the sound waves bouncing around.  You can buy or make bass traps to even out the bass, abosorber panels to absorb high frequencies and diffusers to break up reflected sound and scatter it.  You can spend as much as you want, but most rooms respond well to soft furniture, rugs (if a wood floor), and hard furniture to break up sound.  The worst thing in the world is to have a bunch of hard, parellel walls for the sound to bounce off of again and again.  And a square room, which makes all these flaws worse.
 
Since you have some money and seem hell-bent to spend it, take the time to get your value.  I'd visit a few music stores to try out speakers  and a few studios, too.  Most studios will show you around if you are interested and may let you listen to some music over their systems in their room.  Many engineers are happy to go on about their stuff - just remember they are a business, not a free educational school.
 
If I was buying new monitors, I'd make sure my room wasn't horrible and in the $2000 range buy some Pelonis.  I think they are $2500 for an 7 or 8 inch woofer, which is just about the right size since those will replicate frequencies down to 40-50 Hz well.  Pelonis also make bookshelf speakers which I've used a pro studios.  They are small (5 inch?) but make great secondary monitors or good primary monitors for a small studio (if you can check the bass else where or get their subwoofer for it).  The small ones are a $1000 and the sub about the same.  Personally, I prefer single unit speakers.  In the sub $1000 range the Yamaha MSP 7s would be my choice.  I can't promise those will work for 30 years like my old NS-8s, but they will do a good job outputting the signal you give them and stay out of the way.  The msp-5s are used in studios for the secondary nearfields.
 
It is hard to waste your money when you spend on quality, but you can get the better deal w/ a little patience and research.  Then spend the most you can afford and use it w/o looking back.  Everytime I upgrade my computer/tablet the next month there is a better deal.  I've learned not to look through the adds for stuff I just bought.
 
Have fun.