I've got RS-5 and JUNO-D LE...I can select only one part of the performance to play at a time...There's no way to have all these 3 sounds (piano, string, and orchestra hit) on my keyboard simultaneously...So I wonder how it is done on Juno DS series.
On the Juno DS, piano would be part 1, strings would be part 2, and parts 1 and 2 would be layered (same key range). You would assign the orchestra hit to be part 3. Since every part in a Performance can have its own assignable key range, you could have the piano+strings layered over most of the keyboard, and have another section of keys with the orchestra hits. (To that extent, it's the the same as what you and Biggles are familiar with from Korg Combis.)
Also important is whether you turn the KBD setting on or off for each part. If it is on, it will always play; if it is off it will only play when you select that part with the pad buttons. You can only select one pad button at a time, but if you assign multiple sounds to the same RxCh (receive channel), they will all be enabled/disabled simultaneously with the one button (and each can still have its own key range).
In short, within a
single Performance, you can have whatever combination of splits and layers you want, as long you don't exceed a total of 16 sounds between them. For each of the 16 sounds, you can specify a key range, and you can set KBD to on or off. If you set it to On, the sound will play no matter what. If you set it to Off, it will only play when its associated pad button is selected, or when another sound's associated pad button is selected if that other sound is on the same RxCh.
So for example, you could have layered Piano + Strings playing all the time across whatever section of the keyboard you'd like (i.e. parts 1 and 2, KBD On), an Organ + Vibes split/layer can get added when you hit pad 3 (i.e. use parts 3 and 4, KBD Off, both set to RxCh 3), and then you could switch off the Organ + Vibes and switch in Brass + Synth instead (i.e. use parts 5 and 6, KBD Off, both set to RxCh 5). So while playing piano/strings continuously throughout the song, you can easily switch other sounds in and out as you play, using a single button, with those sounds appearing either over the same keyboard range as your main sound or over different keys. You can also turn KBD off even for your main sound (your 1+2 piano+strings sound in the above example) if you want those sounds to turn off when you switch to other sounds. It's very flexible.
Biggles, I think this is actually beyond what you can do in a Kross. I don't think the Kross has any way to use its 16 buttons to bring in different split/layered sounds in real time as you play. You
can use them to switch from one Combi to another by making them Favorites (you have 8 banks of 16), but any held or decaying notes from the first Combi will cut out when you switch to the second. On the DS, you can similarly do a Kross-Combi-like switch from one Performance to another (either by typing the number of the Performance you want to switch to, or by making them Favorites like on the Kross, where there are 10 banks of 10), and unlike the Kross, previously held/decaying sounds won't disappear, but you may hear an audible glitch because of changing effects, whereas if you switch within a single Performance, there are no glitches.
My take on it is that Kross Combi and Roland Performance are pretty equivalent when calling up different sounds when switching from one song to another, but Roland has the edge for switching among different sounds within a single song... no sound glitches, plus you don't have to use up more Favorite slots. OTOH, a Kross Combi is better if you're trying to integrate internal and external sounds (i.e. if you want your split/layers to include sounds from an external device like an iPad or MIDI sound module), because its Combis can include definable Program Change commands for attached devices, which Roland doesn't do. There's always something...