wpawlley,
I've had the 2480 with
DS90A monitors since 2001 when the 2480 1st came out and I had problems with this initially, too. Here are some things that I did to solve this pretty common problem:
Listen to commercial CDs through the 2480/DS-8's and "learn" where the low end is sitting in the mix. I would concentrate on ,say, the kick drum or bass guitar and just focus on that, then play my song back on the 2480 and try and match the level and tone.
Also, the 2480 has a speaker modeling patch called "super flat". Insert this into the Mastering Room and check your low frequency sound. This patch will tell you when the bottom end has gone too far. Great tool for this purpose.
I've found that the 2480 captures low frequencies very well and have yet to add low EQ to properly recorded drum or bass tracks . However.... I always use the HPF (high pass filter) on EVERY track while mixing down, even if it's set to 20Hz.
This will remove the mud that builds up over mant channels when combined.
Try rolling vocals off around 80Hz to 150Hz. Same with guitar tracks.
Roll bass guitar off to about 30Hz to 40Hz (depending on whether it's a 4 or 5 string bass).
Try rolling the kick drum off at 25Hz or so.
Alot of this really depends on the tone of the instrument and the sound that you're after, but you could use these numbers as a starting point.
Give this a try and let me know if you need more info. Hang in there, this is the roughest part of recording next to capturing good audio.
Hope this helps,
Lucio