When you quote Joe Osborn preferring the studio enviroment, we must know that a studio have acoustics and monitors that intend to be transparent. The goal is to let the monitors being faithfull to any incoming signal. All its acoustic is designed to not interfere on what monitors are producing. So, any adjustments you make on your tone should be truly translated to tape, disk and monitors.
If you feed the desk direct, all you can do is turn knobs on your bass to get the tone. If you use an amp you can choose send the signal after Eq and benefit from your amp's Eq stage (preamp). If you are miking its Cab, you can get its particular tone and all room's reinforcements (since each rooms enhance differents frequencies being produced in it). Anyway you opt, you can rely that monitors will truly reproduce what is being recorded.
If you are used to this practice is easy to know how much of your Tone came from Bass, from Amp, from Cab and Room. But really important should be being aware on how the Bass alone really sounds like, because most of us just know how our Basses sound in a particular room, trough a particular chain of gear, and they all lie in a sense. Amps uses to enhance lows and a Cab can sound really different if it is at floor level (mid scooped), lifted up (open sounding) or near a corner (more fatty). So, listening to your tone through an Amp is like trying to evaluate colors using a colored lens eyeglass.
Now, lets think about live shows...
You have amp and cab, or wedge monitors, it doesn't matter. All that you have to guide you is a unique reference at a particular spot at stage that has nothing to do on how FOH will reproduce tones and how the entire room will reacts to them. Even before turning up your amp, you are probably already sending a DI to FOH system, so you can expect your bass sounding muddy and bassy at stage, just for start.
That happens because lows are omnidirectional and can spread behind FOH as strongly as it spreads ahead. Highs on other hand are very directional and simply can't be heard behind FOH as it would be heard by audience. So, all we have are this overwhelming lows...
If you don't have any monitoring, you probably will cut lows and enhance highs on Bass. But if you send this to FOH with its shiny tweeters, people at audience will hear the ugliest bass tone ever. If your tone at home or any small venue is bass+amp+cab, in a live situation it is bass+desk's channel stripe+FOH (assuming that sound man sooner had solved acoustics issues at this specific ambient).
If you use any bass shy monitor system (as most wedges are), you must be aware to not try compensate its lack of lows. Most of time, the FOH's low leakage will match that bright sounding monitor, but even then is a risk assume that you hear what people are listening. The best bet would be make all adjustments from audience perspective first, using the help of a Series incredible Eq capabilities and/or desk Eq, and just them move to the stage to try to get a decent tone where you'll be during show.
There you can adjust your amp tone to compensate how the room is feeding you at that spot or ask sound man to equalize your monitor send. But keep in mind that not every venue has gear enough to equalize your wedge and you can't tweak onboard preamp to improve how the wedge or amp is sounding on stage without messing with your tone to audicence.
That is when having an Amp on stage is usefull. Since it can get over FOH leakage, you can always tweak its adjustments to perfect your tone at stage without interfering on our direct signal sent to FOH. Remember that much of our effort during sound passage will be missed when people occupy all seats, so new adjustments are needed during the performance and is helpfull not depending on sound crew to solve monitoring issues quickly and satisfyingly (they will be concerned on how sound is coming to audience first, then they will care about the singer needs and is better not bet when they will care on the bass...).
ps.: Sorry for long post and hope that you can understand my lousy english (everytime I feel writing as a child tryng to express myself as a grown up)
