It appears that only Max Combo that gets you your letter grades x.o I dunno if getting +Fever matters, but that'll technically get you a higher combo by the end by hitting Fever sooner, if that matters or if it scales instead...
Kuda has a Max Combo of 1110 according to the wiki, so if its...
First 50 notes w/ 1x = 50 notes total, then Fever
Next 50 notes w/ 2x = 150 notes total, then Fever
Next 50 notes w/ 3x = 300 notes total, then Fever
Next 100 notes w/ 4x = 700 notes total, then fever
Remaning 860 notes w/ 5x = 4300 combo + 700 = 5000 combo max, so there's still room for a good 161 more combo, which should be done by hitting Fever sooner, and by not losing Fever throughout the song, which may be why he's only getting an S. ( 4839 / 5000 = 96.78% Combo Rate )
Same with Ladymade Star 6k HD, with 1054 combo (therefore losing 56 * 5 = 280 combo compared to Kuda_, that's still 4720 max combo, which you're pretty close... ( 4664 / 4720 = 98.8% Combo Rate ) <- So close
Then again, if +Fever helps, then its a lot easier, at least on other songs, I don't seem to have a problem SSS some things, and i have like +8 Fever or so... i mean i'm not as good to get 99.0+ on Kuda or Ladymade Star on 6k, but on the songs i can do i get a lot of SS and SSS without getting crazy high scores such as this.
I think its 100 Maxes to get from x4 to x5... or either x5 to the next x5... i'm not sure)
I mean honestly, do you use any +Fever items? Since i would think a lot of those would be SSS, but its probably the combo holding you back. In any case, if you're getting at least that without +Fever, then you'd probably SSS easily with them x.o;
Edit: Since Baldfalk (3449/3505 = 98.4%) did For Seasons -Air Guitar Mix- 6k NM, i decided to do that as my test :x
Here's it with all my equips on. Simple SSS, no problem... I'd still need to test and get around the 3450ish combo and see if the borderline is still the same with or without +Fever
http://i389.photobucket.com/albums/o...404_065859.jpg
Here's the next set without any equipment, where accuracy is both 99.6%, but a mere 15 difference in combo made the difference between SS and SSS
http://i389.photobucket.com/albums/o...404_070351.jpg ( 3457 / 3505 = 98.6% Combo Rate )
http://i389.photobucket.com/albums/o...404_070930.jpg ( 3472 / 3505 = 99.0% Combo Rate )
Lastly, a run with no fevers hit, a full 811 combo, but of course a D ranking ><
http://i389.photobucket.com/albums/o...404_073113.jpg
Since the Max Combo in this song is 811 on NM (so in the above examples the first 250 notes = 700 combo, and the remaning 561 * 5x = 2805, making a total of 3505 combo, which is damn close (around 33 notes i had), so we're talking about a 1% combo difference from Max Combo...
So its like 99%~100% combo = SSS, else its SS or below. With Fevers, it seems to make it a lot easier for sure, since technically you're going over the 100% limit most likely, since a 3564 / 3505 = 101.6% combo
So in the end, if you want impressive SSS, then do it with Fever +0 at least. Getting Fever makes it much easier it seems.