Thanks Rodilh!
Another cool thing to play around with is having some unique aspect to the start of a lead or keys sound. I guess it would be a ‘transient’ sound. And also try to create a rich sound to start with before filtering away at it.
For example: Here is a sound I made as a ‘basic’ starting point. Try it and save variations and experiment with the settings. It may spark something for you - or not (~.^)
OSC 1 Tun = 23 ~ 26
TRK = OFF
LEV = OFF
WAV = SQR
SUB = OFF
PW = 21~24
ALL Others = default
Page2
NOISE
FAD = 51
LVL = 58
All others = default
OSC2
LVL = 75 (try from very low (eg; 33) for gentle / max for harsh)
WAV = Tr Pulse
PW = -7
SPD =45
PWM =33
All others = default
Page2
SMD= 2 -> 1
AM2 = ON
TRG = ON
All others = default
LFO1
SPD=33
MUL= Tuned 2K
MOD = TRG
WAV = EXP
DST1= PM1
DEP= 45
All others = default
So here is a basic sound with some character maybe like a ‘harmonica’ or something. Now after building up a harmonically rich sound there is something to actually start ‘sculpting’ away from. I think it’s good to have a nice big ‘chunk of clay’ as it were to start with.
As for the filter
For a string sound you might try:
FRQ= 20~45
RES=20=45
OVR= 12~30 (I like about 30)
TRK= 8 (Or to your taste)
DEP=39
Filt2
FRQ=17
RES=35
TYP=PK
All others = default
ENVF
ATK=10
DEC=54
SUS=0
REL=52
SHP= 3
DST= OSC2 PW
DEP= 3~ 19 (soften the string sound)
AMP ENV
ATK = 17~20
DEC= 70
SUS= 30
REL= 45
SHP= 7
CHO = Great place to use it if you want a wider string sound
REV= If you like it - I always do on strings.
Other options;
OSC1= 45
AMP ATK= 0
All other settings as above
This makes a cool bass in the low registers and ‘thin’ brass like sound in the uppers if you use filter tracking.
Anyway these are some things to try as starting points.

Not really my kind of thing but didn’t hear anything special while flicking through, mostly the kind of sounds I’d normally associate with A4?