there just wouldn't be time for me to start scrolling or hitting tiny buttons to seamlessly switch from Clarinet to Sax to Piano and then back to say Sax at the end.
I read a bit on things like Ableton, Camelot, Mainstage and wonder is that what I need?
Do I run those live with a Mac or ipad?
If your goal is to be able to quickly change which PSR-EW425 sounds you're playing, no, there is no app that can do that, because the PSR-EW425 does not support being able to use MIDI to change the sounds you're playing from its keyboard. The only way you could use a Mac or iPad to address this would be to use the device to play sounds located in your Mac or iPad (as opposed to sounds built into the keyboard). And then you'd have to use the Mac or iPad itself or some kind of additional MIDI control surface or pedal to control changing the sounds.
MacBook with Mainstage.
That said, consider upgrading your keyboard.
I'd be in the "upgrading your keyboard" camp here.
Mainstage does have the virtue of being both a control environment AND a source of high quality sounds, but at least by itself, is not an easy solution to the problem here, which is a need to change sounds quickly. Instantly changing sounds directly on your Mac during performance--having to somehow place it conveniently and then use its keyboard/mouse/trackpad--would not be a great solution for split second sound changes (and the PSR-EW425 itself is not set up with things like patch select buttons that can easily call up external sounds). So you'd still need to add something (e.g. that additional MIDI control surface or pedal ).
The iPad would be a better operational platform here than the Macbook, because you could place it on the PSR's music rest, and tap the screen to get to the sound you need. Unfortunately, Mainstage does not run on iPad... but there is a "Logic Remote" app that lets you control Mainstage from an iPad. I've never done this and can't speak to how well it works for the instantaneous patch selection goal. But if the OP already owns both the Mac and the iPad, this is something that could be experimented with at minimal cost. Another option could be to go with a completely iPad based system. A self-contained environment like Korg Module might be sufficient; or you could use whatever combination of apps gives you the sounds you want, and access them all through an app like Camelot Pro or Keystage.
But with any of this, I feel like we may be getting into somewhat complicated and/or cumbersome solutions to address a very simple shortcoming. Unless there is some desire for some of the other capabilities these platforms offer, I think these approaches might be overkill for the task at hand, in terms of complexity and time investment, unless OP already has some familiarity with doing these kinds of things. I think the easiest solution is to switch to a keyboard that lets you change sounds quickly, which is why I'm in the "upgrading your keyboard" camp.
It is a case of ifs and buts, which depend upon how you use your e series which is a basic arranger.
Do you use the Style play modes during your performances?
If you do then a more upmarket Arranger will provide more of what you seek.
Yes, all of the above is based on basic "live" keyboard functions. If he's actually making use of arranger functions, that further complicates the software approach (e.g. Mainstage does not include arranger functions). There's either additional software needed, or you'd have to also consider how to integrate the keyboard's arranger functions with the external sound selection. This is nothing I have experience with.
One of the issue you will be faced with is having a seamless sound transition as you change instruments as not many keyboards support this action.
The Juno does allow this in a limited format, that is you can switch from one Instrument Combination to another without a break but the caveat being it is dependent upon instruments used and any FX that may be applied. Others with more experience that I of a Juno should be able to explain more.
You're talking about the Juno DS, which is discontinued. OP asked about the Juno D6, the replacement for the DS61. The new model is improved in this respect. e.g. see
https://support.roland.com/hc/en-us...-switching-scenes-cause-a-brief-sound-dropout
Following up from above; Would a Psr sx 720 or a Roland Juno D6 be a suitable upgrade from my psr E425?
This also gets to the question of whether you use the arranger (auto-accompaniment) functions of your E425. The PSR SX-720 is a higher end arranger than your E425; the Juno D has advantages of its own but is not an arranger. Though in either case, you'd be moving down from 76 to 61 keys, which you may or may not find important. (The Juno D is also available with 76 keys, that's the Juno D7.)
As for addressing the specific question of being able to quickly switch from sound to sound, the Juno D does have definable quick sound change buttons... 8 banks of 16 buttons. So you can put your clarinet, sax, and piano sounds in a bank, and instantly, seamlessly change from any sound to any other just by tapping one of those definable buttons located right above the keys. These buttons actually call up "Scenes" which can be individual sounds, or split/layered combinations of sounds. And if you do expand to adding external sounds from a Mac or iPad, these scenes can include external sounds as well.
I don't follow arrangers as much, and don't know how the SX-720 compares in this respect.
