An ALL NOTES OFF message is sent whenever you change programs from one to another. This is particularly true when moving from Voice to Voice in VOICE mode. This is commonly built-in to avoid just what you consider a "feature". No one wants the sound of one instrument hanging on into the newly selected one. Seriously, that would be just horrible.

But wait, that is just what you are requesting. I stated this just so you become aware that what you are requesting is NOT at all a normal, real world situation. Far from it... First, strings, in the real world, do not have sustain pedals, and any single musician switching instruments has to stop playing one in order to start playing another. That's real world. Try it!

Now, that said, we recognize *exactly* what you are requesting. in fact! it is a very common request. As a keyboard player you want 128 notes of polyphony so you can be bigger than most Orchestras, you want to play all your sounds *and* be able to switch between them as if physics and the real world limitations don't exist.
We are the same way 🙂 being a keyboard player, too!!!!

What Yamaha has done on the Motif, MO/MOXF and MX series (and on the newer S-series as well) to work around the 'laws of physics' is to allow you place 16 instruments in a multi setup called a MIXING. Each VOICE is placed in a separate PART, addressable via a separate MIDI channel. This allows the performer to switch Transmit Channels to address the newly selected PART - this can happen WITHOUT cutting off the current sound. You do not send a PROGRAM CHANGE because all 16 Programs are already recalled within the single multi-timbral program. Therefore, no ALL NOTES OFF message is sent, and it is possible to do exactly what you describe.

That said, you will have to test out the MULTI mode on your S08. I'd like to give you a definitive answer that the S08 works like the Motifs, MOs, MOXFs, and MXs work now, but I cannot, regretfully I do not have an S08 here to test, and it's been too many years since I've had one here to play with. I'm trying to remember when we introduced this capability and which products had it. (I kind of feel that the S08 predates this particular feature).

But call up a MULTI, place your favorite sounds side-by-side in a MULTI. Then use the PART SELECT buttons [1]-[16] to change between Parts. For example, put your Strings in PART 1 of the Multi, put your Piano or lead in PART 2. Now from the main MULTI screen you should be able to change transmit channels by simply touching the numbered buttons.

Let us know. If this solves your problem.... (You're welcome!)

If not, and I kind of think the S08 cannot/does not operate this way. ...you might consider updating yourself to the current Yamaha synths which all now allow you the ability to hold a sound on one MIDI Channel while you switch to another and play. They all do this now... By design. Why? Because as keyboard players we want the impossible! But it is very important that the laws of physics BE ANNOYING... This is what causes progress as we develop workarounds to the previously impossible.

Since 2007 we have introduced something called "XA CONTROL" which is an articulation control designed, in part, to specifically address seamless transitions within the performance of musical sounds... In fact, on all the newer engines you can create a situation to transition between any sounds without any sonic disruption at all. Part of what XPANDED ARTICULATION CONTROL is all about is determining exactly what Elements are sounding at any particular time. This can be used to transition between gestures on a single instrument - like articulating a spicato bow stroke, or executing a legato move on a horn Voice, or (since it is a synthesizer) ... transitioning one complete instrument to another without sonic interruption.

🙂 let us know.