Running a Preamped bass through an Outboard preamp also...

It doesn't make sense to me but I know a lot of guys that do it. If it sounds good, who cares?

 

As long as you have your gain structure right it's fine.

 

Right.

 

You're looking at an increased noisefloor and decreased headroom. If EQ are used to cancel each other for some reason, there may also be phase shifts, but it's questionable if they could be heard.

 

Active basses plug into amps that usually have their own preamps so adding another one to the chain is an incremental rather than a fundamental change. There is no reason it will not work as long as you run it all sensibly. A preamp box at your feet like the preamp in your bass is convenient to adjust. Your main amplifier may be remotely located and inconvenient to adjust. An external preamp may have features that your bass preamp lacks. An external preamp will also work with your passive basses and having a common setup that you know well and can adjust by well honed instinct in an instant for all your basses is a good idea. Yes, there are good reasons to run an active bass through an external preamp.

As with all things you must use it with care. Every active stage in your chain does add a little noise of its own but that is not normally an issue. If you boost some frequency band to the max in every preamp in the chain then yeah, you will eat up all the headroom and almost certainly be clipping. When I do this I set the preamps I don't plan to adjust on the fly to flat and then use only one to do all the adjustments or else I use one to adjust some frequency bands and another to adjust other frequency bands. As long as you think through what you will do with each preamp you can avoid trouble with having them daisy-chained.

Ken