OK...now that we know where this is supposed to go, here's this:
Oh, yeah...now THIS is serious business!
Taking the cue from your explanation that this needs to be more of an "open-ended" exploration synth that can ALSO bang hard, this is my end-result. Several things got removed due to non-functionality (video LFOs, 921B VCOs [they need the 921A driver], non-Intellijel tiles [I'm presuming the cab is an Intellijel 7U x 104], uZeus), and others because of the need to correctly add "assistive" modules for others, and a few things (like the effects) because of that as well as the fact that you might get better results from outboard devices. Here's what this is about:
TILES: All Intellijel format now. Stereo audio IN, dual 1 to 3 buffered mults, Duatt, 1 channel of MIDI interfacing, Noise Tools (contains noise and random sources, sample and hold, slew limiter, and clock), another Duatt, Stereo VCA and Stereo OUT. The Duatts can be used as 2-in mono mixers OR as a pair of attenuverters...and yes, you CAN mix inverted and normal signals with these, which you might find very useful for messing with modulation to the VCOs and VCFs. And the Stereo VCA is placed so that you can impose CV level control over your stereo mix prior to the output. FYI, the Intellijel 7U has connectors for MIDI and audio I/O, and those tiles connect to those case connections. Also, this case has 3 Amps on the 12V rails, and since the build tops out at 1600+ mA on the +12 and just under an Amp on the -12, this should run pretty cool as you're nowhere near the max current load.
ROW 1: Envelope follower (for use with the external input to extract envelope/gate from incoming audio amplitude), dual slew limiters (with selectable direction response), then a Doepfer A-111-4 which is a Quad analog VCO. Following this is a MakeNoise Modemix, a dual ring-mod/mixer with which you can seriously mess with the A-111-4's outputs. You can also screw with those with the Bifold, a multi-input wavefolder and crossfader. Then we have some digital VCOs, clones of Mutable's Braids and Plaits, with a Happy Nerding FM Aid to allow FM crossmod between these (or these and a VCO from the A-111-4). After this is a 4-in mixer for summing, then there's a pair of VCFs...a Steiner-Parker Synthacon clone, very prone to wild, messed-up and very COOL filtering, plus a Doepfer A-121-2 multimode VCF which is more "sensible". Veils clone next, then a Happy Nerding PanMix, which is a six-input stereo mixer with CV panning capability. It's also got a headphone preamp for handy monitoring and tuning.
ROW 2: I chose a Temps Utile clone for your master clocking/initial sequencing. The Fractio Solum is a CVable clock divider/multiplier and the first of a few modules for screwing with the clocking. The Ladik Composer is a psuedo-random pattern generator, and their Comparator allows you to extract gate/trigs from LFOs, EGs, and the like. So then, I put a Tesseract VC Logics after those so that you can use the dual Boolean gates there to really mess with rhythm patterns and the like; with the incoming gate/trig/clocking from these first modules, you can go as wild as you want with clocking and pattern generation. Then sequencers...a 4-step Ladik is first, then a Qu-bit Octone for your 8-stepper with quantizing. The idea here is that you can use the 4-stepper for transpositions of the Octone, or even as a wholly separate 4-step CV sequencer.
Then, we've got LFOs...a little Quad LFO from Doepfer, then the Noise Reap uLoaf, which is a dual LFO with some very fun crossmodulation capabilites. Right after those, there's a Tenderfoot attenuverting mixer for cooking up complex LFO results, followed by half of a Veils clone from Antumbra. Following those, then there's the Maths and a Quadrax (quad envelope) with its Qx expander placed with the intention of letting it cross-connect with the Maths to turn BOTH modules into something completely over the top as modulation sources go. And you can even break out Quadrax EGs to use "normally" while you've got one or two handy to mess with the Maths' behavior. After this, I had to cheat a bit on the layout, but managed to include Bastl's well-regarded GrandPa and its expander for sampling.
Yes, it's denser. Yes, it's more complex. And yes, it overshoots costs...but this is a serious, comprehensive experimentation modular that ALSO operates in a straightforward manner for live gigs. The idea was to take things beyond the "beeps and boops" to some really wild, tripped-out territory while still being basic enough to work just fine for that original intent. Now, the effects, I already mentioned. Seriously, get on eBay or Reverb and pick up some cheap AF outboard processing while it's still going for dimes on the dollar. Then regarding the drum sounds...just get a proper drum machine, and you'll have a syncable device which has a UI that's intended for drums and controlling them properly. And it's cheaper than trying to assemble one in the build, too.
One other thing as well...ALWAYS consider what a build like this connects to outside of its box. If you don't have a decent small stereo mixer at this point...well, now's the time to get one. Then you can properly use outboard effects, mix this thing with some drum machines, and so on. If you keep those things in mind WHILE designing a build, you'll find you can eliminate a lot of superfluous modules...which then lets you make the functionality of the build denser and more capable. As for what to get...well, this might be surprising, but I'm going to suggest hunting down an ORIGINAL Mackie 1202...the square, boxy-looking one. Yeah, it's over 25 years since these were made, but I still use mine and it works 100% even with lots of live gigs and general abuse since I got it in 1993. You can't kill them. Look for some rack multieffects such as a Yamaha SPX90 (great, gritty 14-bit effects) or a Lexicon LXP-15 ($1400+ new, now about $125), and you'll be on the right track. And NEVER neglect the power of stompboxes...I have a "library" of about 40+ of those, with many being very oddly-behaving Chinese models, all of which have something interesting and unique that they can contribute to the results. So, LITERALLY think outside this particular box, and on outward to start considering what to build up AROUND this, with the modular as a centerpiece.