phaolo: Hello,
has anyone ever managed to enable EAX on Win7+ OSes and without a Creative SB card (via Alchemy)?
Yes.
The simplest solution is the best.
https://community.pcgamingwiki.com/files/file/28-creative-alchemy-universal/
Disregard the "This solution is deprecated" bit. I find it's still, by far, the easiest, simplest & most reliable one. So far, I've had 100% success rate with this tool, even with weird, obscure on-board soundcards.
For Realtek, the most common on-board soundcards, you have 3D Soundback you can download from their website. It works well, but it's stuck on version 0.1, and Universal ALchemy also works pretty well on those. It's a matter of preference.
MIDI, VirtualMIDISynth is the easiest, simplest solution and it's free.
Of course, these are fixes for laptops. The best solution for a gaming desktop is a Soundblaster Z. Yes, Creative business practices are not the best, and onboard audio is very good nowadays & you can make do with them, but the Z series is fairly cheap, and I "converted" a couple of people with just a short "before & after" comparison. There is a huge, very noticeable improvement in sound quality.