Paul,

Looking at that photo, I think you already have a reasonable monitoring setup with the combination of phones and VRM, and the hi-fi speaker setup that you have.

I really don't think you are going to hear a marked difference in your mixing capabilities with purchase of even a pretty expensive set of monitors. Several reasons - you would need to spend quite a bit on acoustic treatment of your mix/monitor room - get the desk out of the corner, etc.

The points raised above about hi-fi speakers having a signature sound built in are true. What is also true is that your mixing space also has a similar issue with a 'signature sound' built in that you don't even know about unless you spend the time and energy and dollars to fix that. It is likely much larger of an issue than the delta between the hi-fi speakers and any set of monitors you would set in the same location.

And you will get as many opinions as to which are the 'best' monitors for your space as you will replies.

A recent edition of Electronic Musician has a reasonable guide for your question - but your existing phones/VRM MIGHT be better than purchase of any additional gear. http://www.emusician.com/gear/0769/master-class-%E2%80%93-choosing-studio-monitors/153461

Your mix you posted last week sounded great. I'm guessing you came to it mostly through phones/VRM use.

Why mix on phones? One reason is that it is a primary delivery method to most listeners these days. This was not true 30 years ago, and progressively has become more and more the 'consumption' of music over time. No, don't mix on phones exclusively - but there is much more reason to do it now than in the days when this was considered a major faux pas.

Your going round and round in circles is typical, and with the small size of your room and your choice of putting your mix location head position in a corner, is very likely what causes your muddy issue, not just the fact that you are using hi-fi speakers instead of nearfield monitors. This is a low frequency issue, and both will have similar radiation patterns for low frequency. Mids and highs are where you start to see radiation pattern differences between nearfield monitor speakers and hi-fi speakers. The laws of physics are not easily broken.

Here's the main issue with your setup that unless you can move a bunch of stuff around in that room, you will still have low frequency issues. I'm quoting from the EM article here:
"When placing your monitors, follow the manufacturer’s guide, but here are some basic suggestions. Most nearfield cabinets should be roughly five or six feet apart, and the same distance from your ears. Each speaker should be the same distance from its respective side wall, or imaging will suffer. Tweeters should be at ear height. Don’t assume that a vertically oriented speaker can be turned on its side and yield accurate results. In some cases, the tweeter must be removed and rotated 90 degrees; in other cases, the manufacturer will warn against alternate positions. Ditto for “toeing in” the speaker. Be aware of whether or not the speakers are intended to be close to a wall or not. Every time you place a speaker near a boundary, the low-frequency response will bump up. Keep the cabinets out of corners for the same reason."

That muddiness you are referring to can be traced directly, at least in part or perhaps in full, to your existing speaker placement. Putting a nice set of nearfields in the same place may not change your ability to mix properly for low frequency.

-Scott