2 DI boxes or stereo Direct

[maxpiano]

If need only your NS3 in the monitor, have you considered using the Headphones output for that? Then, if you also want to send stereo to the FOH yes you need 2 DIs (or a stereo=dual channel DI)

Headphones for on stage? No, haven’t considered. Thought iem would be better choice.

I didn't mean that, I meant using headphones output to feed your monitor speaker anyway, as clarified some posts later, you may use the 1-4 Output Routing option of NS3 to do the same using OUT 3 or 4 for the monitor. Someone else suggested IEMs

[Spider]

I think some effects will disappear when routed away from outputs 1 and 2. The Leslie sim is one of them. I run my Organ through output 3 and it removes the Leslie sim automagically.

DI boxes are very useful! I've always had them in my rig for 35+ years. Sound engineers at venues large and small are always happy with this. Lately my DI is connected to my mixer, whether that is the built in DIs in the Radial KL-8 or Key Largo.

Again, I don't own a NS3 but Maxpiano confirmed that you can have two duplicate outputs from all 4 channel outs (minus the leslie). That sounds ideal for sending one to FOH and one to monitor, without needing additional devices (DI, submixer, IEM etc), power supplies and cables.

I didn't say that DIs are not useful, only that for my personal needs, I never felt the urge to own one.
We have a small PA that we use for small gigs with no soundman (bars, restaurants etc), and in those situations the stage is small and cables are short (<10m), so there's no need for any DI.
When we play large gigs with long distances from stage to mixer to monitors etc, the DIs are always provided by the organization (and we request them in the rider, just to be sure). I also often use a small submixer for my stuff, so that reduces even more my need for DIs.
In the end, I investigated DIs many many times (the last one after reading this topic ) but I never found a compelling reason to buy one. A quality one is quite expensive for what it does, and for me it would end up as an emergency backup to throw in the bottom of my cable bag, probably never to be used.
Then every use case is different, of course.

[Spider]

I think some effects will disappear when routed away from outputs 1 and 2. The Leslie sim is one of them. I run my Organ through output 3 and it removes the Leslie sim automagically.

DI boxes are very useful! I've always had them in my rig for 35+ years. Sound engineers at venues large and small are always happy with this. Lately my DI is connected to my mixer, whether that is the built in DIs in the Radial KL-8 or Key Largo.

Again, I don't own a NS3 but Maxpiano confirmed that you can have two duplicate outputs from all 4 channel outs (minus the leslie). That sounds ideal for sending one to FOH and one to monitor, without needing additional devices (DI, submixer, IEM etc), power supplies and cables.

Wait!!! Yesterday I tested with a Piano+pad sound but what you just wrote made me think I should test also with the Organ, due to the Leslie constraints and here we have a big problem, which for me is a stopper (for using Output mode 1-4 for monitoring): if Leslie is engaged you will not hear that section on 3-4 at all, also in that 1-4 configuration!

So I rollback to my original suggestion: if you need to monitor only NS3, you may use headphones output to feed the monitor speakers

[Spider]

using headphones output to feed your monitor speaker
use the 1-4 Output Routing option
IEMs

In addition to those options and the various DIs, I'll throw in another option: why not something like the ART Splitmix?
ART SplitMix4

I have two of them and use them all the time in many different ways, they are amazing. They are a mixer, splitter and patch bay all in one, giving you 4 channels that you can freely mix and/or split as you want, in a tiny passive box with no power supply or any additional inconvenience.
The only drawback is that being passive the signal is quite low, but usually that's a problem only with microphones and acoustic instruments, not with with the line-level outputs of keyboards.

[MEL868]

Mackie MDB-2P Stereo Passive Direct Box
Pro Co IT1 1-channel Line Isolator
Whirlwind DIRECT2 2-channel Passive Instrument Direct Box

Thanks, the top 3 contenders…someone already pointed out the whirl- I didn’t find a ton of blogs on the Mackie, and Pro Co makes a batch of instrument cords for sw, which I’m anxious to try. I was leaning to mono because of caution to passive possibly ‘reduce the level a bit’

But anyway, since I haven’t bought one in yrs and use occasionally it makes sense, at this price point to get one of these in this price range. Thanks

[Hlaalu]

Wait!!! Yesterday I tested with a Piano+pad sound but what you just wrote made me think I should test also with the Organ, due to the Leslie constraints and here we have a big problem, which for me is a stopper (for using Output mode 1-4 for monitoring): if Leslie is engaged you will not hear that section on 3-4 at all, also in that 1-4 configuration!

So I rollback to my original suggestion: if you need to monitor only NS3, you may use headphones output to feed the monitor speakers

Yep... per manual (and per-reality) the Leslie effect is sort of "hard-wired" on outputs 1-2 no matter what.*

The reverb and the compressor, on the other hand, are on whatever output is chosen to be the "main" (and they will happily extend over 3 and 4, if so selected).

*This isn't necessarily bad though. I have my Vent connected to output n. 3, so engaging it will automatically disable the internal sim and go for the Vent.