It cracks me up that the computer specs are listed to a t, which matters not, how about the model number of the speakers. the answer is most likely 42. Just out of curiousity what is the problem you are having.

Apologies if you felt the computer specs were over the top detail-wise. Thought is might be helpful to let you know. Didn't mention the specific Alesis model (MkII actives) as I know they do not posses the characteristics I require. Apologies for the omission.

The "problem" I'm having is two-fold:
one of a veiled mix, with an inability to resolve detail especially in the mids. I wonder whether better A/D/A conversion coupled with a higher standard of monitoring would improve the standard of soundscape that I'm working with. I work with a wide range of music, from studio recorded heavy rock, to folk voice and guitar, and some on location recording of choir/string quartets. It's not simply a microphone/preamp issue as I have DI tracks from various amp-modelling units that I would like to hear in greater detail to mix better.

Second is wanting to hear the bottom end of the mix more tightly. This is probably largely a monitor issue. (I can hear these freqeuncies more clearly on other monitoring systems with the same mix).

As you can see, I have already decided what I feel is best. I'm just testing out this hypothesis on the expert forum to make sure I'm not being daft.

Before you mention it, I have acoustic treatment, especially really good base trapping and mid range absorbers....(auralex)

I don't think the problem you're having is your mics, your pre's or even your converters.

Before you buy anything yet, why not take a representative mix of your best stuff somewhere else, with better speakers and an environment you trust. If it becomes clear your speakers are the weak link in your chain, then it's time to go beyond the Alesis. I don't know those speakers in particular, but I doubt they're going to give you the really professional results you're seeking. I don't know first hand; they may be good speakers for getting everyday/journeyman results, but they're certainly not the last word in mixing and mastering. It sounds like you may be hitting the wall with what they're giving you.

You may want to also look into a subwoofer. I'm not an advocate of huge booming bass or exaggerated low end, but I do want to hear everything, especially when I'm mastering and mixing things. (Not to mention its proper place in 5.1 mixes.)

Only can tell what I prefer :

Brauner Mic

Great River for Neve color
Earthworks ZDT noncolor

RME Hammerfall DSP with a ADI 8 DS
or
RME Fireface

JBL LSR 6328P & 6312SP
or
Genelec 8050A & 7070A