Hi Amliw,
You are welcome :-)
Well, I have to be honest with you, yes that Sinfonion needs a lot for input (actually for the output, the input is still kind of okay), the more you feed it, the more fun it gets and I wasn't joking that the Sinfonion will become the black hole of your system, it really sucks up anyting that comes near to it, you just want to feed it more the get more complicated stuff out of it.
I also bought it a slightly bit too early, but there was a good deal in the regular shop I am going so I couldn't leave it there :-) What I did then was I just didn't use all the channels at the same time yet because I just didn't had enough modules to feed this beast. Then slowly when my setup started to grow I could make more use of the potential of this monster. A monster in a good way, but still a monster ;-)
Well utility modules are always good to have, with or without the Sinfonion, so you might need to look into that issue first then.
Perhaps we should change the question a little bit here from "What does the Sinfonion like to be fed with?" into "What would you like to feed the Sinfonion with?" ;-)
It's really difficult to answer that question of yours because, the Sinfonion is rather flexible and because of the many possibilities it offers you, you really can just almost throw anything to it and it will take it and do some weird or less weird things with it, which all will depends on you, on how you configure it.
But perhaps with trying to give a few examples, you might get a better idea:
For that "The Cry Of The Modular Synth" track, I "fed" the Sinfonion with an input signal... oh yes! For each channel the Sinfonion likes to have an input :-) I usually take an LFO that's flexible in use so when I change the LFO, the behaviour of the Sinfonion changes too. However for the above-mentioned track, I used the Doepfer - A-118-2 noise module and used the random output and used that as the input for channel 1. That's why the "note selection" by Sinfonion behaved a bit weird (and not in always the same kind of rhythm that you might get with an LFO) in that above track; on purpose of course :-)
On the output of each of those Sinfonion channels you could connect those to a simple or complex oscillator, totally up to you. What I didn't do was that I connected the output of a channel first to an oscillator and then started to work on that sound of the oscillator. No, I worked the other way round, it could take me days till I found a nice kind of sound (or an interesting sound), once found only then I decided the channel I wanted to relate that "nice found sound" connected to the Sinfonion. Once I got then a nice tone pattern with/from the Sinfonion then I tried to kind of finalise that sound by an extra touch with yet another filter or effect.
But in the above example of "finding a nice sound" that usually takes some efforts and might use quite some modules to come up with that nice sound.
Once that channel was then ready, I then again started to look for another nice sound that took me again some time and lots of modules and then used that in context with yet another channel on the Sinfonion. Till the Sinfonion was fully fed (or connected all the channels) and then you can start using the Sinfonion in all its glory ;-)
But you are totally right, you need quite an already large system to be able to get the Sinfonion to its rights. ACL is mentioning that also, it's rather meant for medium till large setups than for small setups.
While you saving money for the Sinfonion, look if you have enough oscillators for 3 channels, chords and a nice arpeggio (with all the supporting modules that those oscillators might need). If you find here and there a lack of modules you can start working on that and when you think you are ready, get the Sinfonion :-)
But don't get me wrong here, I don't want to push or force you into any direction or whatsoever, you just do what you like. You don't have to get a Sinfonion. For your wallet it's much better not to take a Sinfonion, not only because of the costs of the Sinfonion but also because of the costs of all the modules you sooner or later will need to keep the Sinfonion (and yourself) happy :-D
Take a few days off and think about it, for these kind of big things you shouldn't rush into it and give it a few good thoughts. Meanwhile have fun with your modular synth and a good weekend. Kind regards, Garfield.
For review reports of Eurorack modules, please refer to https://garfieldmodular.net/ for PDF formatted downloads