Well I actually play guitar in my cover band, but on the demos I record bass as well. The recordings sound great but everytime we record something new I have to spend a lot of time on mixing the bass. The low end is always sooo boomy. I have 2 basses that I use and it's the same issue with both. One bass is a Fender Blacktop P bass with flats and the other is a Squier P bass with roundwounds. I go through the direct out of our GK 1001RB head into our interface. What could be the issue here? Do the P Basses perhaps have too deep of a sound for what we are looking for?
I forgot to mention that part of getting a decent sound on the recordings is cutting the lows and low mids way more than I think should be necessary.
Record flat. If you have a "sharp" sounding kick, you should mix with a "fat" sounding bass....and vice versa. Cut a few dB's in the 240hZ range ...often clears things up. Reevaluate your monitor system as well... make sure that what it is "telling your ears" is indeed what is "being recorded". P Basses are the most recorded electric bass in history. You should be able to get a good sound with them.
The lows that you're getting when you go direct in are usually lost with most amplifiers/speakers as are the extreme highs. An amp simulations plug in would probably solve your issues with less work than playing with eq.
First thing that occurred to me is to just use another route into the interface instead of the GK and compare. Not familiar with the direct out of the 1001RB, but before you go too nuts I would try with a vanilla DI box to rule out that the DI out of the GK is contributing to this.
Be sure the direct out selector switch is set to "pre", or tone controls are set near flat with the contour at 0 if it set to "post".
something i found out, is that you may be clipping your monitors. (making them work too hard, making a "pop" or "clicking" noise) I would recomend either looking at your monitors to make sure they are not blown, or use headphones instead.
Make sure the output on the amp is set pre eq, or set the eq flat if that is not an option. If you still need to eliminate boominess, cut the eq freq below 200. Also, I've always had better luck tone wise if I run two channels while recording, one off the direct out from the amp, and the second from a mic positioned 3 feet from the speaker cabinet. This allows you to mix both the true sound of the bass (off the amp output) and the true sound of the amp (off the mic).