@vsch your setup seems nice, and your separate post shows that you have good ears and that you're on the right path AFAIK. Keep going!
The Kef 3001 are old speakers which are not available at all anymore. Not knowing Kef I don't know the current model.
I've tried used. I've found black 5.1 packs, but I need either white or very light wood for my interior. I can keep looking.
The Genelec 8030c are active monitors, right? So how would that work with a 3800? Did you bypass their amp or the 3800's amp?
Here a used pair of 8030c's seems to cost about 700 €. Genelec doesn't seem to have Home Cinema packs though.
Why would you have a second sub? The SVS wasn't enough?
For my future system, I've always imagined front floorstanders, but satellites could also work if paired with a decend sub like the SVS, even for Hi-Fi purposes.
I know about OCA and I intend to use his german sorcery once I get my new system

I think I'm pretty decided on the 3800, I just need the right speakers to go with it.
Thanks for the kind words.
Yes, the KEF 3001s are pretty old. I once read that they served as a prototype for some of the technology that went into the Blades -- not sure whether that's true, though. The build- and sound-quality are great in IMHO, and sometimes you can get a used set for ~400 EUR. There is an improved "se" edition that they also offered in white. If you are patient, you may find such a set popping up on a marketplace. (There are also the Kef E305, which are the successor but made out of plastic instead of aluminium. A friend of mine has them. They sound good too, but particularly the center speaker is a simpler 2-way design.)
Yes, the Genelec 8030c are active studio monitors. Objectively, they are on a whole different level than the HTS-3001 and have some of the highest preference scores on spinorama.org.
Here is
@amirm 's review. I love them in my nearfield 2.1 desk setup. However, in my untreated living room at 2.8m, they don't sound noticeably better than the HTS-3001 after applying
@OCA 's room correction and crossing over to the sub(s) at 120 Hz. I think the room reflections and reverberations smear out the advantage of the 8030c in such a less than ideal setting. (Moreover, the more channels you have, the less the quality of the individual speakers matters. If I remember correctly,
@Floyd Toole talks about this in his recent
AES presentation. This is also the reason why you should assess speaker quality in mono.)
Yes, you can connect the 8030c (or any other active studio monitor) to the Denon 3800h. You just need an RCA -> XLR cable. It worked flawlessly in my case, but you have to be careful of ground loops that could cause humming.
Regarding active monitors: have you looked at Kali IN-8v2 or IN-5, or the even cheaper 2-way JBL 305P MKII? If you can live with the looks, the need to have a power cable to each speaker (and maybe no auto standby), and the SPL limits, they seem to offer great bang for the buck.
Why the second sub? The SB-1000 is more than powerful enough to keep up with the HTS-3001 speakers. I recently added a used HTB2 sub in the opposite corner of the room to deal with a null in the frequency response and to even out the overall bass response. At the same time, I upgraded the room correction from A1 Acoustica to the brand-new A1 Acoustix from
@OCA . The system has definitely never sounded better with more "enveloping and immersive" bass, but I don't know whether this is mainly due to the second sub or the improved room correction.