Okay, so atm I monitor using my stereo speakers. They are quite old, but I think good quality.

Now, the actual stereo unit has a 5 band graphic EQ.

Would there be a way of working out which frequencies my speakers boost and compensating using the EQ? Hence making them a little more accurate with flatter response.

I know that this is no replacement for buying actual proper monitors, but I don't have the funds for that at the moment so please don't suggest it . This was just an idea, if not I'll just put the stereo's EQ to flat.
You can get measurement kits using special mics. Look it up.

Or you can ditch accuracy, do the NS10 and cut the highs and mids :p